Advertisement

Dietary Interventions and Quality of Life: A Systematic Review of the Literature

  • Tiffany L. Carson
    Correspondence
    Address for correspondence: Tiffany L. Carson, PhD, Department of Medicine, University of Alabama at Birmingham, 1720 2nd Avenue South MT 639, Birmingham, AL 35205; Phone: (205) 934-1443; Fax: (205) 975-7199
    Affiliations
    Division of Preventive Medicine, Department of Medicine, School of Medicine, University of Alabama at Birmingham, Birmingham, AL

    Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL

    Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL
    Search for articles by this author
  • Bertha Hidalgo
    Affiliations
    Department of Biostatistics, Section on Statistical Genetics, University of Alabama at Birmingham; Birmingham, AL
    Search for articles by this author
  • Jamy D. Ard
    Affiliations
    Department of Epidemiology and Prevention, Wake Forest School of Medicine, Wake Forest Baptist Medical Center, Winston Salem, NC
    Search for articles by this author
  • Olivia Affuso
    Affiliations
    Nutrition Obesity Research Center, University of Alabama at Birmingham, Birmingham, AL

    Department of Epidemiology, School of Public Health; University of Alabama at Birmingham, Birmingham, AL
    Search for articles by this author
Published:November 01, 2013DOI:https://doi.org/10.1016/j.jneb.2013.09.005

      Abstract

      Objective

      To systematically review the literature to examine whether there has been adequate assessment of the effects of dietary intervention on quality of life (QOL) independent of weight loss, assess which instruments are being used to measure nutrition-related QOL, identify gaps in the literature, and suggest future directions.

      Design

      Systematic review guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement.

      Results

      A total of 24 studies were eligible for inclusion. The Short Form–36 Health Survey was the most widely used instrument to assess QOL. Other disease-specific instruments were used. Several different dietary approaches (eg, low carbohydrate, low calorie, low fat, combinations) were recommended. Across studies, QOL generally improved after participating in behavioral weight loss interventions, but findings revealed a lack of evidence to definitively determine whether reported changes in QOL were a result of weight loss or independent of it.

      Conclusions and Implications

      It is important to consider how making broad dietary recommendations for all individuals might affect overall QOL in both positive and negative directions when considering factors other than weight loss and health improvement. If dietary interventions are adversely affecting QOL in other domains (eg, social, economic) and this relationship is not being detected or reported by current research practices, barriers for successful and sustainable dietary changes may not be fully understood.

      Key Words

      Introduction

      Behavioral lifestyle interventions that include recommendations for dietary changes are widely used to promote weight loss, which, for some individuals, results in decreased risk for several chronic diseases including type 2 diabetes,
      • Knowler W.C.
      • Barrett-Connor E.
      • Fowler S.E.
      • et al.
      Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin.
      hypertension,
      • Appel L.J.
      • Champagne C.M.
      • Harsha D.W.
      • et al.
      Effects of comprehensive lifestyle modification on blood pressure control: main results of the PREMIER clinical trial.
      and some cancers.
      • Chlebowski R.T.
      • Blackburn G.L.
      • Thomson C.A.
      • et al.
      Dietary fat reduction and breast cancer outcome: interim efficacy results from the Women's Intervention Nutrition Study.
      These interventions include a range of dietary approaches (eg, low fat/low calorie, low carbohydrate, low energy density) for creating the energy deficit needed for weight loss. Indeed, the implementation of a variety of dietary interventions has produced at least modest weight loss for many and substantial weight loss for some. However, despite the apparent benefits of dietary interventions on weight and weight-related health outcomes, the independent effect of these various dietary interventions on quality of life (QOL) remains unclear.
      Broadly, QOL is a multidimensional concept that includes an individual's subjective evaluation of both positive and negative aspects of life.
      The WHOQOL Group
      The World Health Organization Quality of Life Assessment. Development and psychometric properties.
      Specific areas of study may explore QOL related to a particular discipline, such as a specific disease, overall health, or weight. Research examining the effect of weight loss on QOL is largely mixed depending on whether the QOL measure is obesity specific, and on the intervention modality.
      • Maciejewski M.L.
      • Patrick D.L.
      • Williamson D.F.
      A structured review of randomized controlled trials of weight loss showed little improvement in health-related quality of life.
      • Fontaine K.R.
      • Barfosky I.
      Obesity and health-related quality of life.
      In addition, much of these data are limited to examining only changes in QOL related to weight loss and improvement in health conditions. This approach fails to consider an independent effect that implementing behavior change, altering dietary consumption, or simply participating in an intervention program may have on an individual independent of weight loss. Figure 1 proposes a conceptual model for the relationship between dietary intake and QOL. It illustrates the relationship between dietary intake and several life domains that may ultimately influence QOL. This figure highlights important areas to consider when examining how dietary changes may affect QOL in both positive and negative ways and regardless of whether weight loss occurs. For example, whereas weight loss that results from dietary change may improve some domains of QOL for some individuals, dietary change may also have negative effects on QOL by affecting that individual's economic situation or social interactions, which are often food centered. Thus, if an individual's QOL is diminished in some way as a result of dietary change, that individual may be less likely to continue to implement the change, which will ultimately limit successful weight loss and/or weight loss maintenance.
      Figure thumbnail gr1
      Figure 1Conceptual model of the potential impact of dietary intake on quality of life.
      To date, the majority of nutrition- or weight-related QOL research has focused on the relationship between dietary intake and QOL by way of physical measures such as weight loss or risk factor reduction. However, it is plausible that making dietary changes can have a meaningful effect—positive or negative—on QOL through other avenues that are less well understood. Guided by the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement,
      • Moher D.
      • Liberati A.
      • Tetzlaff J.
      • Altman D.G.
      Preferred Reporting Items for Systematic Reviews and Meta-Analyses: the PRISMA Statement.
      the purpose of this report was to systematically review the literature to examine whether there has been adequate assessment of the effects of dietary intervention on QOL independent of weight loss, to assess which instruments are currently being used to measure nutrition-related QOL, to identify gaps in the current literature, and to suggest future research directions.

      Methods

      Published results of nutrition/dietary interventions intended to promote weight loss were reviewed. The primary outcome of interest was change in QOL. Secondary outcomes of interest were changes in weight and attrition.
      With the assistance of a reference librarian, articles were retrieved using searches performed in PubMed, CINAHL, Psychinfo, Scopus, and the Cochrane Library. Searches for MeSH headings and key words were conducted to identify publications for inclusion, using the following limits: date, human studies, age and language. Searches were performed using combinations of the following terms: “quality of life,” “nutrition,” “diet,” “food,” “weight,” “weight loss,” and “intervention.”

       Inclusion and Exclusion Criteria

      All studies were evaluated according to the following inclusion criteria: (1) The study reported QOL as an outcome; (2) the study was a dietary intervention; (3) the study was intended to promote weight loss; (4) the intervention was at least 12 weeks in duration; (5) the study was a human study; (6) study participants were adults (age ≥ 19 years); (7) the publication was available in the English language; (8) the study was conducted in the United States; and (9) the publication date was between January 1, 1990 and August 31, 2012. Studies were excluded if the intervention provided food, surgery, or pharmaceutical means for weight loss, unless a dietary intervention arm that met the inclusion criteria was included in the trial as a comparison group. Studies were also excluded if they met none of the stated inclusion criteria (ie, studies were required to meet all inclusion criteria to be evaluated for this report).

       Filtering Steps

      All search results were first combined into a master reference database and duplicate references were deleted. Studies that clearly did not meet inclusion criteria based on reading the titles and abstracts were excluded. For all remaining papers, the full text of the paper was read to determine whether the study met inclusion criteria.

       Methodological Quality Assessment

      Each study was assessed for bias using the Methodological Index for Non-Randomized Studies, a tool for assessing risk of bias in both non-comparative and comparative studies.
      • Slim K.
      • Nini E.
      • Forestier D.
      • Kwiatkowski F.
      • Panis Y.
      • Chipponi J.
      Methodological index for non-randomized studies (minors): development and validation of a new instrument.
      Two co-authors (B.H. and O.A.) independently rated each study (not reported = 0, reported but inadequate = 1, or reported and adequate = 2) for the following items: clearly stated aim, inclusion of consecutive patients, prospective data collection, appropriate end points, unbiased assessment of study end point, appropriate follow-up period, < 5% loss to follow-up, prospective calculation of the sample size. For comparative studies, items also included an adequate control group, contemporary groups, baseline equivalence of groups, and adequate statistical analyses. These ratings were used as the basis for the overall score of quality for each study, with the possibility of 24 points for comparative studies and 16 points for non-comparative studies. The 2 reviewers discussed the ratings and arrived at an agreement on the quality score in each study. When consensus could not be reached, a third co-author (T.L.C.) reviewed the study to adjudicate the quality score.

       Data Extraction

      Data were extracted by the co-authors individually using data extraction tables. Data extracted included study name and dates of study, intervention setting and duration, sample size, gender and race composition of sample, anthropometrics, QOL instrument used, and changes in QOL.

      Results

      The initial search yielded 302 articles (Figure 2). After removal of 3 duplicates, title and abstract review of the remaining results led to exclusion of 219 articles. The primary reasons for exclusion at this point in the review were studies not meant to promote weight loss, studies conducted outside the United States, surgical interventions, or pediatric populations. Thus, 80 articles were deemed potentially eligible. Of the 80 potentially eligible articles, 56 were excluded because they did not meet all eligibility criteria. Descriptive characteristics of the 24 included studies are shown in Table 1. All but 3
      • Blissmer B.
      • Riebe D.
      • Dye G.
      • Ruggiero L.
      • Greene G.
      • Caldwell M.
      Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects.
      • Malone M.
      • Alger-Mayer S.A.
      • Anderson D.A.
      The lifestyle challenge program: a multidisciplinary approach to weight management.
      • Ross K.M.
      • Milsom V.A.
      • Rickel K.A.
      • et al.
      The contributions of weight loss and increased physical fitness to improvements in health-related quality of life.
      of the included studies were randomized trials ranging in duration from 12 to 104 weeks in treatment and duration. Study samples included mostly women (50% to 100% of participants) for all included studies except Evangelista et al
      • Evangelista L.S.
      • Heber D.
      • Li Z.
      • Bowerman S.
      • Hamilton M.A.
      • Fonarow G.C.
      Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study.
      and Pope et al.
      • Pope L.
      • Harvey-Berino J.
      • Savage P.
      • et al.
      The impact of high-calorie-expenditure exercise on quality of life in older adults with coronary heart disease.
      Figure thumbnail gr2
      Figure 2Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram detailing the review filtering process.
      Table 1Characteristics of Included Studies (n = 24)
      StudyDesign, SettingIntervention Groups, Component DetailsTreatment Duration, Follow-up DurationSample Characteristics (Group Size, n; Age, y [% Female Gender])Quality of Life Instrument Used
      Ackerman et al
      • Ackermann R.T.
      • Edelstein S.L.
      • Narayan K.M.
      • et al.
      Changes in health state utilities with changes in body mass in the Diabetes Prevention Program.
      RCT, clinicalG1: placebo

      G2: metformin (increased to 1,700 mg/d)

      G3: lifestyle: goal-based diet and PA intervention; 150 min/wk moderate PA; 1,200–2,000 kcal/d based on baseline weight and dietary fat to < 25% of total calories
      104 wk, 104 wkG1: n = 1,082; 50.6 (68%)

      G2: n = 1,073; 50.6 (68%)

      G3: n = 1,079; 50.6 (68%)
      SF-36 and QWB-SA
      Barham et al
      • Barham K.
      • West S.
      • Trief P.
      • Morrow C.
      • Wade M.
      • Weinstock R.S.
      Diabetes prevention and control in the workplace: a pilot project for county employees.
      RCT, worksiteG1: wait-list control

      G2: lifestyle: goal-based diet and PA intervention; 150 min/wk moderate PA; 1,200–2,000 kcal/d based on baseline weight and dietary fat to < 25% of total calories
      52 wk, 52 wkG1: n = 24; 51.2 (81%)

      G2: n = 21; 51.1 (81%)
      HRQOL SF-12, IWQOL, 3-Factor Eating Questionnaire
      Blissmer et al
      • Blissmer B.
      • Riebe D.
      • Dye G.
      • Ruggiero L.
      • Greene G.
      • Caldwell M.
      Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects.
      Cohort, clinicalG1: increased F/V and whole grains, set fat goals of 20%/25%/30% of total calories24 wk, 24 wkG1: n = 144; 50.2 (78%)SF-36
      Darga et al
      • Darga L.L.
      • Magnan M.
      • Mood D.
      • Hryniuk W.M.
      • DiLaura N.M.
      • Djuric Z.
      Quality of life as a predictor of weight loss in obese, early-stage breast cancer survivors.
      RCT, communityG1: control: received National Cancer Institute's Action Guide to Healthy Eating and Food Guide Pyramid pamphlets with no other instruction

      G2: Weight Watchers

      G3: One-on-one dietary counseling of calorie/fat restriction

      G4: combined Weight Watchers and individualized counseling group
      24 wk, 24 wkOverall (not group specific): n = 39; 52.1 (100%)FACT-An and FACT-G
      Davis et al
      • Davis N.J.
      • Tomuta N.
      • Isasi C.R.
      • Leung V.
      • Wylie-Rosett J.
      Diabetes-specific quality of life after a low-carbohydrate and low-fat dietary intervention.
      RCT, clinic/universityG1: low-CHO diet; 2-wk phase of CHO restriction of 20–25 g daily with gradual 5-g increase

      G2: low-fat diet; 25% of energy needs based on baseline weight
      52 wk, 52 wkG1: n = 55; 54 (81%)

      G2: n = 50; 53 (74%)
      SF-36 and IWQOL-Lite
      Evangelista et al
      • Evangelista L.S.
      • Heber D.
      • Li Z.
      • Bowerman S.
      • Hamilton M.A.
      • Fonarow G.C.
      Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study.
      RCT, clinicalG1: AHA recommended conventional diet

      G2: high protein; 40% CHO, 30% protein, 30% fat

      G3: standard protein, hypocaloric; 55% CHO, 15% protein, 30% fat
      12 wk, 12 wkG1: n = 4; 62.2 (25%)

      G2: n = 5; 56.4 (20%)

      G3: n = 5; 58.6 (20%)
      Minnesota Living With Heart Failure questionnaire
      Fontaine et al
      • Fontaine K.R.
      • Barofsky I.
      • Andersen R.E.
      • et al.
      Impact of weight loss on health-related quality of life.
      RCT, communityG1: control: lifestyle PA to increase PA throughout day

      G2: diet + PA; traditional aerobics and reduced-calorie, reduced-fat diet; 1,000 kcal less than maintenance
      13 wk, 13 wkG1: n = not stated; 37.3 (53.3%)

      G2: n = not stated; 36.4 (46.7%)
      SF-36, BDI
      Heshka et al
      • Heshka S.
      • Anderson J.W.
      • Atkinson R.L.
      • et al.
      Weight loss with self-help compared with a structured commercial program: a randomized trial.
      RCT, clinicG1: self-help program; 20-min counseling sessions with nutritionist and provision of self-help resources

      G2: commercial Weight Watchers weight loss program: food plan, activity plan, and cognitive restructuring behavior modification plan
      104 wk, 104 wkG1: n = 211; 45 (82%)

      G2: n = 212; 44 (87%)
      SF-36 and IWQOL-Lite
      Imayama et al
      • Imayama I.
      • Alfano C.M.
      • Kong A.
      • et al.
      Dietary weight loss and exercise interventions effects on quality of life in overweight/obese postmenopausal women: a randomized controlled trial.
      RCT, community and cancer research centerG1: wait-list control

      G2: lifestyle; goal-based diet and PA intervention; 150 min/wk moderate PA; 1,200–2,000 kcal/d based on baseline weight and dietary fat < 30% of total calories

      G3: exercise; 45 min/d MVPA, 5 d/wk

      G4: diet and exercise combined
      52 wk, 52 wkG1: n = 118; 54.7 (100%)

      G2: n = 87; 57.4 (100%)

      G3: n = 117; 58.1 (100%)

      G4: n = 117; 58 (100%)
      SF-36
      Kennedy et al
      • Kennedy B.M.
      • Paeratakul S.
      • Champagne C.M.
      • et al.
      A pilot church-based weight loss program for African-American adults using church members as health educators: a comparison of individual and group intervention.
      RCT, communityG1: general nutrition education, group

      G2: general nutrition education, individual
      24 wk, 24 wkG1: n = 20; 44 (NP)

      G2: n = 20; 44 (NP)
      IWQOL
      Ladson et al
      • Ladson G.
      • Dodson W.C.
      • Sweet S.D.
      • et al.
      The effects of metformin with lifestyle therapy in polycystic ovary syndrome: a randomized double-blind study.
      RCT, clinicalG1: metformin (increased to 2,000 mg/d) + caloric restriction; 500 kcal less than maintenance

      G2: lifestyle-alone caloric restriction; 500 kcal less than maintenance
      24 wk, 24 wkG1: n = 55; 29 (100%)

      G2: n = 59; 28.8 (100%)
      PCOS HRQOL
      Malone et al
      • Malone M.
      • Alger-Mayer S.A.
      • Anderson D.A.
      The lifestyle challenge program: a multidisciplinary approach to weight management.
      Cohort, universityG1: general nutrition education, group20 wk, 20 wkG1: n = 90; 48 (82%)SF-36
      Melanson et al
      • Melanson K.J.
      • Dell'Olio J.
      • Carpenter M.R.
      • Angelopoulos T.J.
      Changes in multiple health outcomes at 12 and 24 weeks resulting from 12 weeks of exercise counseling with or without dietary counseling in obese adults.
      RCT, communityG1: exercise only

      G2: lifestyle; 25% to 40% calories from meal replacements with F/V, whole grains, if dairy; 50% CHO, 25% protein, 25% fat
      12 wk, 24 wkG1: n = 47; 42.3 (85.1%)

      G2: n = 43; 43.0 (86.0%)
      SF-36
      Pope et al
      • Pope L.
      • Harvey-Berino J.
      • Savage P.
      • et al.
      The impact of high-calorie-expenditure exercise on quality of life in older adults with coronary heart disease.
      RCT, communityG1: standard cardiac rehabilitation + caloric restriction; 500 kcal less than maintenance

      G2: high-calorie expenditure + caloric restriction; 500 kcal less than maintenance
      20 wk, 20 wkG1: n = 36; 63 (16.7%)

      G2: n = 38; 64 (21%)
      SF-36
      Rejeski et al
      • Rejeski W.J.
      • Focht B.C.
      • Messier S.P.
      • Morgan T.
      • Pahor M.
      • Penninx B.
      Obese, older adults with knee osteoarthritis: weight loss, exercise, and quality of life.
      RCT, universityG1: control; group sessions of usual care

      G2: diet; emphasis on changing eating habits to lower caloric intake

      G3: exercise; 60 min, 3 d/wk

      G4: combined diet and exercise
      72 wk, 72 wkG1: n = 68; 68.6 (66.7%)

      G2: n = 73; 68.1 (74.1%)

      G3: n = 69; 68.96 (73.8%)

      G4: n = 68; 68.5 (73.3%)
      SF-36
      Rippe et al
      • Rippe J.M.
      • Price J.M.
      • Hess S.A.
      • et al.
      Improved psychological well-being, quality of life, and health practices in moderately overweight women participating in a 12-week structured weight loss program.
      Randomized prospective trial, Weight Watchers InternationalG1: control; maintain regular lifestyle

      G2: diet and exercise; commercial Weight Watchers program

      G3: exercise; expenditure of 3,139.5 kJ in self-selected PA; gradual increase to maximum of 6,379 kJ
      12 wk, 12 wkG1: n = 40; 35.6 (100%)

      G2: n = 30; 37.4 (100%)
      SF-36
      Ross et al
      • Ross K.M.
      • Milsom V.A.
      • Rickel K.A.
      • et al.
      The contributions of weight loss and increased physical fitness to improvements in health-related quality of life.
      Cohort, communityG1: lifestyle; goal-based diet and PA intervention; 150 min/wk moderate PA; 1,200–2,000 kcal/d based on baseline weight and dietary fat to < 25% of total calories24 wk, 24 wkG1: n = 274; 59.0 (100%)SF-36
      Villareal et al
      • Villareal D.T.
      • Banks M.
      • Sinacore D.R.
      • Siener C.
      • Klein S.
      Effect of weight loss and exercise on frailty in obese older adults.
      RCT, universityG1: control; maintain regular lifestyle

      G2: diet and exercise; caloric restriction of 750 kcal less than maintenance
      26 wk, 26 wkG1: n = 10; 71.1 (60%)

      G2: n = 17; 69.4 (71%)
      SF-36
      Villareal et al
      • Villareal D.T.
      • Chode S.
      • Parimi N.
      • et al.
      Weight loss, exercise, or both and physical function in obese older adults.
      RCT, universityG1: control

      G2: diet; 500–750 kcal less than daily energy requirement

      G3: exercise; 90-min aerobic, strength, and flexibility exercises

      G4: diet and exercise combined
      52 wk, 52 wkG1: n = 27; 69.0 (67%)

      G2: n = 26; 70.0 (65%)

      G3: n = 26; 70.0 (62%)

      G4: n = 28; 70.0 (57%)
      SF-36
      von Gruenighen et al
      • von Gruenigen V.E.
      • Gibbons H.E.
      • Kavanagh M.B.
      • Janata J.W.
      • Lerner E.
      • Courneya K.S.
      A randomized trial of a lifestyle intervention in obese endometrial cancer survivors: quality of life outcomes and mediators of behavior change.
      RCT, clinical/communityG1: control; usual care brochure

      G2: general nutrition/PA education
      24 wk, 52 wkG1: n = 23; 55.5 (100%)

      G2: n = 22; 54.0 (100%)
      FACT-G
      Williamson et al
      • Williamson D.A.
      • Rejeski J.
      • Lang W.
      • et al.
      Impact of a weight management program on health-related quality of life in overweight adults with type 2 diabetes.
      RCT, multi-site clinicalG1: control; diabetes support and education

      G2: lifestyle; goal-based diet and PA intervention; 175 min/wk moderate PA; 1,200–2,000 kcal/d based on baseline weight and dietary fat to < 25% of total calories
      52 wk, up to 11.5 yG1: n = 2,575; 58.8 (59.7%)

      G2: n = 2,570; 58.6 (59.4%)
      SF-36, BDI-II
      Wolf et al
      • Wolf A.M.
      • Conaway M.R.
      • Crowther J.Q.
      • et al.
      Translating lifestyle intervention to practice in obese patients with type 2 diabetes: Improving Control with Activity and Nutrition (ICAN) study.
      RCT, universityG1: control; usual care brochure

      G2: general nutrition/PA education
      52 wk, 52 wkG1: n = 71; 53.4 (58%)

      G2: n = 73; 53.3 (62%)
      SF-36
      Womble et al
      • Womble L.G.
      • Wadden T.A.
      • McGuckin B.G.
      • Sargent S.L.
      • Rothman R.A.
      • Krauthamer-Ewing E.S.
      A randomized controlled trial of a commercial internet weight loss program.
      RCT, communityG1: weight loss manual; 1,200-1,500 kcal/d self-selected diet of conventional foods based on Food Guide Pyramid

      G2: commercial program; e-diets; conventional foods with caloric restriction based on body mass index
      52 wk, 52 wkG1: n = 24; 43.3 (100%)

      G2: n = 23; 44.2 (100%)
      SF-36
      Yancy et al
      • Yancy Jr., W.S.
      • Almirall D.
      • Maciejewski M.L.
      • Kolotkin R.L.
      • McDuffie J.R.
      • Westman E.C.
      Effects of two weight-loss diets on health-related quality of life.
      RCT, Veterans AdministrationG1: low-CHO/low-ketogenic diet; < 20 g/d

      G2: low-fat diet; < 30% of daily energy
      24 wk, 24 wkG1: n = 59; 44.2 (75%)

      G2: n = 60; 45.6 (78%)
      SF-36
      AHA indicates the American Heart Association; BDI, Beck Depression Inventory; CHO, carbohydrates; F/V, fruits and vegetables; FACT-G/An, Functional Assessment of Cancer Therapy–General/Anemia; G1, G2, G3, Group 1, 2, or 3; HRQOL, Health-Related Quality of Life; IWQOL, Impact of Weight on Quality of Life; MVPA, moderate and vigorous physical activity; NP, not provided; PA, physical activity; PCOS, polycystic ovarian syndrome; QWB-SA, Quality of Well-Being Scale–Self-administered; RCT, randomized controlled trial; SF-36, Short Form–36 Health Survey.

       Methodological Quality Assessments

      The mean quality score was 19.6 ± 2.6 (81.8%) for comparative studies and 8.7 ± 0.9 (54.2%) for non-comparative studies, respectively. Unbiased end point assessment (ie, blinding), sample size calculation, and loss to follow-up received the 3 lowest ratings (range, 0.71–1.29 out of 2) across all items irrespective of study design. These findings suggest that attention is needed to improve the methods and reporting of studies in the nutrition literature assessing QOL.

       Quality of Life Measures

      Eight different surveys were used to measure QOL in the included studies. The majority (71%) of the studies
      • Blissmer B.
      • Riebe D.
      • Dye G.
      • Ruggiero L.
      • Greene G.
      • Caldwell M.
      Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects.
      • Malone M.
      • Alger-Mayer S.A.
      • Anderson D.A.
      The lifestyle challenge program: a multidisciplinary approach to weight management.
      • Ross K.M.
      • Milsom V.A.
      • Rickel K.A.
      • et al.
      The contributions of weight loss and increased physical fitness to improvements in health-related quality of life.
      • Pope L.
      • Harvey-Berino J.
      • Savage P.
      • et al.
      The impact of high-calorie-expenditure exercise on quality of life in older adults with coronary heart disease.
      • Ackermann R.T.
      • Edelstein S.L.
      • Narayan K.M.
      • et al.
      Changes in health state utilities with changes in body mass in the Diabetes Prevention Program.
      • Davis N.J.
      • Tomuta N.
      • Isasi C.R.
      • Leung V.
      • Wylie-Rosett J.
      Diabetes-specific quality of life after a low-carbohydrate and low-fat dietary intervention.
      • Heshka S.
      • Anderson J.W.
      • Atkinson R.L.
      • et al.
      Weight loss with self-help compared with a structured commercial program: a randomized trial.
      • Melanson K.J.
      • Dell'Olio J.
      • Carpenter M.R.
      • Angelopoulos T.J.
      Changes in multiple health outcomes at 12 and 24 weeks resulting from 12 weeks of exercise counseling with or without dietary counseling in obese adults.
      • Rejeski W.J.
      • Focht B.C.
      • Messier S.P.
      • Morgan T.
      • Pahor M.
      • Penninx B.
      Obese, older adults with knee osteoarthritis: weight loss, exercise, and quality of life.
      • Rippe J.M.
      • Price J.M.
      • Hess S.A.
      • et al.
      Improved psychological well-being, quality of life, and health practices in moderately overweight women participating in a 12-week structured weight loss program.
      • Villareal D.T.
      • Banks M.
      • Sinacore D.R.
      • Siener C.
      • Klein S.
      Effect of weight loss and exercise on frailty in obese older adults.
      • Villareal D.T.
      • Chode S.
      • Parimi N.
      • et al.
      Weight loss, exercise, or both and physical function in obese older adults.
      • Wolf A.M.
      • Conaway M.R.
      • Crowther J.Q.
      • et al.
      Translating lifestyle intervention to practice in obese patients with type 2 diabetes: Improving Control with Activity and Nutrition (ICAN) study.
      • Womble L.G.
      • Wadden T.A.
      • McGuckin B.G.
      • Sargent S.L.
      • Rothman R.A.
      • Krauthamer-Ewing E.S.
      A randomized controlled trial of a commercial internet weight loss program.
      • Yancy Jr., W.S.
      • Almirall D.
      • Maciejewski M.L.
      • Kolotkin R.L.
      • McDuffie J.R.
      • Westman E.C.
      Effects of two weight-loss diets on health-related quality of life.
      • Williamson D.A.
      • Rejeski J.
      • Lang W.
      • et al.
      Impact of a weight management program on health-related quality of life in overweight adults with type 2 diabetes.
      • Fontaine K.R.
      • Barofsky I.
      • Andersen R.E.
      • et al.
      Impact of weight loss on health-related quality of life.
      • Imayama I.
      • Alfano C.M.
      • Kong A.
      • et al.
      Dietary weight loss and exercise interventions effects on quality of life in overweight/obese postmenopausal women: a randomized controlled trial.
      used the Short Form–36, a generic tool for assessing QOL using 36 items and including both a physical and mental component summary.
      • Ware J.E.
      • Kosinski M.
      • Keller S.D.
      SF-36 Physical and Mental Health Summary Scales: A User's Manual.
      Four studies
      • Davis N.J.
      • Tomuta N.
      • Isasi C.R.
      • Leung V.
      • Wylie-Rosett J.
      Diabetes-specific quality of life after a low-carbohydrate and low-fat dietary intervention.
      • Heshka S.
      • Anderson J.W.
      • Atkinson R.L.
      • et al.
      Weight loss with self-help compared with a structured commercial program: a randomized trial.
      • Barham K.
      • West S.
      • Trief P.
      • Morrow C.
      • Wade M.
      • Weinstock R.S.
      Diabetes prevention and control in the workplace: a pilot project for county employees.
      • Kennedy B.M.
      • Paeratakul S.
      • Champagne C.M.
      • et al.
      A pilot church-based weight loss program for African-American adults using church members as health educators: a comparison of individual and group intervention.
      used the Impact of Weight on Quality of Life–Lite, which was designed to specifically assess QOL related to weight.
      • Kolotkin R.L.
      • Head S.
      • Hamilton M.
      • Tse C.K.
      Assessing impact of weight on quality of life.
      Other disease-specific instruments (eg, Minnesota Living With Heart Failure Questionnaire, Functional Assessment of Cancer Therapy–General, and Polycystic Ovarian Syndrome Health–Related Quality of Life) were employed in 4 of the included studies.
      • Evangelista L.S.
      • Heber D.
      • Li Z.
      • Bowerman S.
      • Hamilton M.A.
      • Fonarow G.C.
      Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study.
      • Darga L.L.
      • Magnan M.
      • Mood D.
      • Hryniuk W.M.
      • DiLaura N.M.
      • Djuric Z.
      Quality of life as a predictor of weight loss in obese, early-stage breast cancer survivors.
      • Ladson G.
      • Dodson W.C.
      • Sweet S.D.
      • et al.
      The effects of metformin with lifestyle therapy in polycystic ovary syndrome: a randomized double-blind study.
      • von Gruenigen V.E.
      • Gibbons H.E.
      • Kavanagh M.B.
      • Janata J.W.
      • Lerner E.
      • Courneya K.S.
      A randomized trial of a lifestyle intervention in obese endometrial cancer survivors: quality of life outcomes and mediators of behavior change.
      Recommended dietary interventions included calorie restriction alone; fat restriction alone; calorie and fat restriction combined; low-carbohydrate, high-protein, low-sodium/high-potassium, commercial programs such as Weight Watchers; or a general “healthy diet” recommendation. Calorie restriction was the most frequently endorsed approach. With the exception of 3 studies,
      • Pope L.
      • Harvey-Berino J.
      • Savage P.
      • et al.
      The impact of high-calorie-expenditure exercise on quality of life in older adults with coronary heart disease.
      • Ladson G.
      • Dodson W.C.
      • Sweet S.D.
      • et al.
      The effects of metformin with lifestyle therapy in polycystic ovary syndrome: a randomized double-blind study.
      • von Gruenigen V.E.
      • Gibbons H.E.
      • Kavanagh M.B.
      • Janata J.W.
      • Lerner E.
      • Courneya K.S.
      A randomized trial of a lifestyle intervention in obese endometrial cancer survivors: quality of life outcomes and mediators of behavior change.
      all treatment arms with any type of dietary intervention component reported a within-group improvement in QOL (Table 2). Similarly, all active treatment arms reported some weight loss, although the amount ranged from 0.8 to 10.0 kg (Table 2). Based on reported analyses, 4 studies clearly demonstrated that changes in QOL were independent of weight loss,
      • Blissmer B.
      • Riebe D.
      • Dye G.
      • Ruggiero L.
      • Greene G.
      • Caldwell M.
      Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects.
      • Davis N.J.
      • Tomuta N.
      • Isasi C.R.
      • Leung V.
      • Wylie-Rosett J.
      Diabetes-specific quality of life after a low-carbohydrate and low-fat dietary intervention.
      • Rejeski W.J.
      • Focht B.C.
      • Messier S.P.
      • Morgan T.
      • Pahor M.
      • Penninx B.
      Obese, older adults with knee osteoarthritis: weight loss, exercise, and quality of life.
      • Yancy Jr., W.S.
      • Almirall D.
      • Maciejewski M.L.
      • Kolotkin R.L.
      • McDuffie J.R.
      • Westman E.C.
      Effects of two weight-loss diets on health-related quality of life.
      whereas 11 studies indicated that changes were likely a result of weight loss (Table 2).
      • Ross K.M.
      • Milsom V.A.
      • Rickel K.A.
      • et al.
      The contributions of weight loss and increased physical fitness to improvements in health-related quality of life.
      • Evangelista L.S.
      • Heber D.
      • Li Z.
      • Bowerman S.
      • Hamilton M.A.
      • Fonarow G.C.
      Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study.
      • Pope L.
      • Harvey-Berino J.
      • Savage P.
      • et al.
      The impact of high-calorie-expenditure exercise on quality of life in older adults with coronary heart disease.
      • Ackermann R.T.
      • Edelstein S.L.
      • Narayan K.M.
      • et al.
      Changes in health state utilities with changes in body mass in the Diabetes Prevention Program.
      • Heshka S.
      • Anderson J.W.
      • Atkinson R.L.
      • et al.
      Weight loss with self-help compared with a structured commercial program: a randomized trial.
      • Williamson D.A.
      • Rejeski J.
      • Lang W.
      • et al.
      Impact of a weight management program on health-related quality of life in overweight adults with type 2 diabetes.
      • Fontaine K.R.
      • Barofsky I.
      • Andersen R.E.
      • et al.
      Impact of weight loss on health-related quality of life.
      • Imayama I.
      • Alfano C.M.
      • Kong A.
      • et al.
      Dietary weight loss and exercise interventions effects on quality of life in overweight/obese postmenopausal women: a randomized controlled trial.
      • Darga L.L.
      • Magnan M.
      • Mood D.
      • Hryniuk W.M.
      • DiLaura N.M.
      • Djuric Z.
      Quality of life as a predictor of weight loss in obese, early-stage breast cancer survivors.
      • von Gruenigen V.E.
      • Gibbons H.E.
      • Kavanagh M.B.
      • Janata J.W.
      • Lerner E.
      • Courneya K.S.
      A randomized trial of a lifestyle intervention in obese endometrial cancer survivors: quality of life outcomes and mediators of behavior change.
      Based on information provided, the role of weight loss in QOL change was unclear for the remaining 9 studies.
      • Malone M.
      • Alger-Mayer S.A.
      • Anderson D.A.
      The lifestyle challenge program: a multidisciplinary approach to weight management.
      • Melanson K.J.
      • Dell'Olio J.
      • Carpenter M.R.
      • Angelopoulos T.J.
      Changes in multiple health outcomes at 12 and 24 weeks resulting from 12 weeks of exercise counseling with or without dietary counseling in obese adults.
      • Villareal D.T.
      • Banks M.
      • Sinacore D.R.
      • Siener C.
      • Klein S.
      Effect of weight loss and exercise on frailty in obese older adults.
      • Villareal D.T.
      • Chode S.
      • Parimi N.
      • et al.
      Weight loss, exercise, or both and physical function in obese older adults.
      • Wolf A.M.
      • Conaway M.R.
      • Crowther J.Q.
      • et al.
      Translating lifestyle intervention to practice in obese patients with type 2 diabetes: Improving Control with Activity and Nutrition (ICAN) study.
      • Womble L.G.
      • Wadden T.A.
      • McGuckin B.G.
      • Sargent S.L.
      • Rothman R.A.
      • Krauthamer-Ewing E.S.
      A randomized controlled trial of a commercial internet weight loss program.
      • Barham K.
      • West S.
      • Trief P.
      • Morrow C.
      • Wade M.
      • Weinstock R.S.
      Diabetes prevention and control in the workplace: a pilot project for county employees.
      • Kennedy B.M.
      • Paeratakul S.
      • Champagne C.M.
      • et al.
      A pilot church-based weight loss program for African-American adults using church members as health educators: a comparison of individual and group intervention.
      • Ladson G.
      • Dodson W.C.
      • Sweet S.D.
      • et al.
      The effects of metformin with lifestyle therapy in polycystic ovary syndrome: a randomized double-blind study.
      Independent changes in QOL were noted, although not consistently observed, in studies of several different strategies for weight loss, including fat restriction,
      • Blissmer B.
      • Riebe D.
      • Dye G.
      • Ruggiero L.
      • Greene G.
      • Caldwell M.
      Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects.
      calorie restriction,
      • Rejeski W.J.
      • Focht B.C.
      • Messier S.P.
      • Morgan T.
      • Pahor M.
      • Penninx B.
      Obese, older adults with knee osteoarthritis: weight loss, exercise, and quality of life.
      and studies including low-carbohydrate recommendations (Table 3).
      • Davis N.J.
      • Tomuta N.
      • Isasi C.R.
      • Leung V.
      • Wylie-Rosett J.
      Diabetes-specific quality of life after a low-carbohydrate and low-fat dietary intervention.
      • Yancy Jr., W.S.
      • Almirall D.
      • Maciejewski M.L.
      • Kolotkin R.L.
      • McDuffie J.R.
      • Westman E.C.
      Effects of two weight-loss diets on health-related quality of life.
      Table 2Quality of Life and Weight Change Outcomes, by Study Group
      Study AuthorsAttrition by Study Group (%)Baseline Weight, kgWeight Change by Study Group, kgWithin-Group QOL ImprovementBetween-Group Differences in QOL ChangeQOL Independent of Weight Change? (Yes/No/Cannot Determine)
      Ackerman et al
      • Ackermann R.T.
      • Edelstein S.L.
      • Narayan K.M.
      • et al.
      Changes in health state utilities with changes in body mass in the Diabetes Prevention Program.
      Placebo: 0.0

      Metformin: 0.0

      kcal/fat restriction: 0.0
      Placebo: 93.89

      Metformin: 91.5

      kcal/fat restriction: 87.2
      Placebo: −0.4

      Metformin: −2.7

      kcal/fat restriction: −6.8
      Placebo: no

      Metformin: no

      kcal/fat restriction: yes
      YesNo
      Barham et al
      • Barham K.
      • West S.
      • Trief P.
      • Morrow C.
      • Wade M.
      • Weinstock R.S.
      Diabetes prevention and control in the workplace: a pilot project for county employees.
      Control: NP

      kcal/fat restriction: NP
      Control: 96.5

      kcal/fat restriction: 107.3
      Control: +0.7

      kcal/fat restriction: −2.3
      Control: yes

      kcal/fat restriction: yes
      YesCannot determine
      Blissmer et al
      • Blissmer B.
      • Riebe D.
      • Dye G.
      • Ruggiero L.
      • Greene G.
      • Caldwell M.
      Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects.
      Fat restriction: 24.0Fat restriction: 89.7Fat restriction: −5.6Fat restriction: yesNAYes
      Darga et al
      • Darga L.L.
      • Magnan M.
      • Mood D.
      • Hryniuk W.M.
      • DiLaura N.M.
      • Djuric Z.
      Quality of life as a predictor of weight loss in obese, early-stage breast cancer survivors.
      ,
      Attrition and baseline values for body weight were not provided by group. Thus, the overall sample average is reported for each group. Also, weight loss outcomes were combined as shown in the table.
      Control: 23.0

      Commercial diet: 23.0

      kcal/fat restriction: 23.0

      Combination: 23.0
      Control: 94.5

      Commercial diet: 94.5

      kcal/fat restriction: 94.5

      Combination: 94.5
      Control and commercial diet: −0.5

      kcal/fat restriction and combination: −8.7
      Control: yes

      Commercial diet: yes

      kcal/fat restriction: yes

      Combination: yes
      UnclearNo
      Davis et al
      • Davis N.J.
      • Tomuta N.
      • Isasi C.R.
      • Leung V.
      • Wylie-Rosett J.
      Diabetes-specific quality of life after a low-carbohydrate and low-fat dietary intervention.
      Low-CHO: 19.0

      Fat restriction: 19.0
      Low-CHO: 93.6

      Fat restriction: 101.0
      Low-CHO: –3.1

      Fat restriction: –3.1
      Low-CHO: yes

      Fat restriction: yes
      NoYes
      Evangelista et al
      • Evangelista L.S.
      • Heber D.
      • Li Z.
      • Bowerman S.
      • Hamilton M.A.
      • Fonarow G.C.
      Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study.
      Control: 0.0

      High protein: 0.0

      kcal restriction: 0.0
      Control: 109.6

      High protein: 110.8

      kcal restriction: 99.5
      Control: –1.5

      High protein: –9.9

      kcal restriction: −5.6
      Control: yes

      High protein: yes

      kcal restriction: yes
      YesNo
      Fontaine et al
      • Fontaine K.R.
      • Barofsky I.
      • Andersen R.E.
      • et al.
      Impact of weight loss on health-related quality of life.
      Control: NP

      kcal/fat restriction: NP
      Control: 85.2

      kcal/fat restriction: 87.2
      Control: −7.0

      kcal/fat restriction: −8.7
      Control: yes

      kcal/fat restriction: yes
      NoNo
      Heshka et al
      • Heshka S.
      • Anderson J.W.
      • Atkinson R.L.
      • et al.
      Weight loss with self-help compared with a structured commercial program: a randomized trial.
      Control: 25.0

      Commercial: 28.0
      Control: 93.1

      Commercial: 94.2
      Control: −0.1

      Commercial: −3.0
      Control : yes

      Commercial: yes
      NoNo
      Imayama et al
      • Imayama I.
      • Alfano C.M.
      • Kong A.
      • et al.
      Dietary weight loss and exercise interventions effects on quality of life in overweight/obese postmenopausal women: a randomized controlled trial.
      Control: 0.0

      kcal/fat restriction: 0.0

      Exercise: 1.0

      Combination: 0.0
      Control: 30.7 (BMI)

      kcal/fat restriction: 31.0 (BMI)

      Exercise: 30.7 (BMI)

      Combination: 31.0 (BMI)
      Control: not stated

      kcal/fat restriction: −7.2

      Exercise: −2.0 kg

      Combination: −8.9
      Control: yes

      kcal/fat restriction: yes

      Exercise: yes

      Combination: yes
      YesNo
      Kennedy et al
      • Kennedy B.M.
      • Paeratakul S.
      • Champagne C.M.
      • et al.
      A pilot church-based weight loss program for African-American adults using church members as health educators: a comparison of individual and group intervention.
      Healthy diet, group: 20.0

      Healthy diet, individual: 0.0
      Healthy diet, group: 103.7

      Healthy diet, individual: 103.4
      Healthy diet, group: −3.1

      Healthy diet, individual: −3.4
      Healthy diet, group: no

      Healthy diet, individual: no
      NoNA
      Ladson et al
      • Ladson G.
      • Dodson W.C.
      • Sweet S.D.
      • et al.
      The effects of metformin with lifestyle therapy in polycystic ovary syndrome: a randomized double-blind study.
      Drug + kcal restriction: 72.0

      kcal restriction: 60.0
      Drug + kcal restriction: 102.7

      kcal restriction: 104
      Drug + kcal restriction: −3.4

      kcal restriction: −2.0
      Drug + kcal restriction: no

      kcal restriction: yes
      NoCannot determine
      Malone et al
      • Malone M.
      • Alger-Mayer S.A.
      • Anderson D.A.
      The lifestyle challenge program: a multidisciplinary approach to weight management.
      Healthy diet: 57.0Healthy diet: 100.9Healthy diet: −4.1Healthy diet: yesNoCannot determine
      Melanson et al
      • Melanson K.J.
      • Dell'Olio J.
      • Carpenter M.R.
      • Angelopoulos T.J.
      Changes in multiple health outcomes at 12 and 24 weeks resulting from 12 weeks of exercise counseling with or without dietary counseling in obese adults.
      Exercise: 59.6

      kcal restriction: 49.8
      Exercise: 84.3

      kcal restriction: 88.8
      Exercise: −0.4

      kcal restriction: −7.1
      Exercise: no

      kcal restriction: yes
      Not statedCannot determine
      Pope et al
      • Pope L.
      • Harvey-Berino J.
      • Savage P.
      • et al.
      The impact of high-calorie-expenditure exercise on quality of life in older adults with coronary heart disease.
      Standard rehabilitation + kcal restriction: 5.6

      High activity + kcal restriction: 2.6
      Standard rehabilitation + kcal restriction: 95.4

      High activity + kcal restriction: 93.5
      Standard rehabilitation + kcal restriction: −3.7

      High activity + kcal restriction: −8.2
      Standard rehabilitation + kcal restriction: no

      High activity + kcal restriction: yes
      YesNo
      Rejeski et al
      • Rejeski W.J.
      • Focht B.C.
      • Messier S.P.
      • Morgan T.
      • Pahor M.
      • Penninx B.
      Obese, older adults with knee osteoarthritis: weight loss, exercise, and quality of life.
      Control: 22.0

      kcal restriction: 20.0

      Exercise: 18.0

      Combination: 24.0
      Control: 95.8

      kcal restriction: 95.1

      Exercise: 94.1

      Combination: 91.9
      control: −1.2

      kcal restriction: −5.4

      Exercise: −2.4

      Combination: −4.0
      Control: yes

      kcal restriction: yes

      Exercise: yes

      Combination: yes
      YesYes
      Rippe et al
      • Rippe J.M.
      • Price J.M.
      • Hess S.A.
      • et al.
      Improved psychological well-being, quality of life, and health practices in moderately overweight women participating in a 12-week structured weight loss program.
      Control: 35.0

      Commercial: 25.0
      Control: 82.1

      Commercial: 81.2
      Control: −1.3

      Commercial: −6.1
      Control: yes

      Commercial: yes
      YesNo
      Ross et al
      • Ross K.M.
      • Milsom V.A.
      • Rickel K.A.
      • et al.
      The contributions of weight loss and increased physical fitness to improvements in health-related quality of life.
      kcal/fat restriction: 15.0kcal/fat restriction: 96.3kcal/fat restriction: −10kcal/fat restriction: yesNANo
      Villareal et al
      • Villareal D.T.
      • Banks M.
      • Sinacore D.R.
      • Siener C.
      • Klein S.
      Effect of weight loss and exercise on frailty in obese older adults.
      Control: 0.0

      kcal restriction: 0.0
      Control: 103.2

      kcal restriction: 99.7
      Control: +0.7

      kcal restriction: −8.2
      Control: yes

      kcal restriction: yes
      YesCannot determine
      Villareal et al
      • Villareal D.T.
      • Chode S.
      • Parimi N.
      • et al.
      Weight loss, exercise, or both and physical function in obese older adults.
      Control: 0.0

      kcal restriction: 0.0

      Exercise: 0.0

      Combination: 0.0
      Control: 101.0

      kcal restriction: 104.1

      Exercise: 99.2

      Combination: 99.1
      Control: −0.1

      kcal restriction: −9.7

      Exercise: −0.5

      Combination: −8.6
      Control: no

      kcal restriction: yes

      Exercise: yes

      Combination: yes
      YesCannot determine
      Von Gruenighen et al
      • von Gruenigen V.E.
      • Gibbons H.E.
      • Kavanagh M.B.
      • Janata J.W.
      • Lerner E.
      • Courneya K.S.
      A randomized trial of a lifestyle intervention in obese endometrial cancer survivors: quality of life outcomes and mediators of behavior change.
      Control: 10.0

      Healthy diet, individual: 22.0
      Control: 41.1 (BMI)

      Healthy diet, individual: 43.5 (BMI)
      Control: −1.4

      Healthy diet, individual: −3.5
      Control: no

      healthy diet, individual: no
      NoNo
      Williamson et al
      • Williamson D.A.
      • Rejeski J.
      • Lang W.
      • et al.
      Impact of a weight management program on health-related quality of life in overweight adults with type 2 diabetes.
      Control: 4.3

      kcal/fat restriction: 2.9
      Control: 100.8

      kcal/fat restriction: 100.5
      Control: −0.9

      kcal/fat restriction: −8.7
      Control: no

      kcal/fat restriction: yes
      YesNo
      Wolf et al
      • Wolf A.M.
      • Conaway M.R.
      • Crowther J.Q.
      • et al.
      Translating lifestyle intervention to practice in obese patients with type 2 diabetes: Improving Control with Activity and Nutrition (ICAN) study.
      Control: 14.0

      Healthy diet, individual: 26.0
      Control: 107.6

      Healthy diet, individual: 107.1
      Control: −0.6

      Healthy diet, individual: −2.4
      Control: yes

      Healthy diet, individual: yes
      YesCannot determine
      Womble et al
      • Womble L.G.
      • Wadden T.A.
      • McGuckin B.G.
      • Sargent S.L.
      • Rothman R.A.
      • Krauthamer-Ewing E.S.
      A randomized controlled trial of a commercial internet weight loss program.
      kcal restriction, manual: 33.3

      kcal restriction, commercial: 34.5
      kcal restriction, manual: 87.9

      kcal restriction, commercial: 93.4
      kcal restriction, manual: −3.3

      kcal restriction, commercial: −0.8
      kcal restriction, manual: yes

      kcal restriction, commercial: yes
      NoCannot determine
      Yancy et al
      • Yancy Jr., W.S.
      • Almirall D.
      • Maciejewski M.L.
      • Kolotkin R.L.
      • McDuffie J.R.
      • Westman E.C.
      Effects of two weight-loss diets on health-related quality of life.
      Low CHO: 25.0

      Fat restriction: 55.0
      Low CHO: 97.8

      Fat restriction: 96.8
      Low CHO: none stated

      Fat restriction: none stated
      Low CHO: yes

      Fat restriction: yes
      YesYes
      BMI indicates body mass index; NA, not available; other abbreviations as in Table 1.
      a Attrition and baseline values for body weight were not provided by group. Thus, the overall sample average is reported for each group. Also, weight loss outcomes were combined as shown in the table.
      Table 3Summary of Dietary Interventions Used in Included Studies and Their Effect on QOL
      Type of Dietary Intervention RecommendationSummary of Intervention Effects on QOL and Supporting Quotations
      Caloric restriction alone
      • 1,200–1,500 kcal/d
      • BMI based
      • Varying proportions of macronutrient intake
      All study interventions of calorie restriction produced improved QOL. No studies clearly indicated whether QOL improvements were independent of weight loss.
      Fat restriction alone
      • ≤ 25% of energy from fat
      All intervention arms endorsing a low-fat diet produced improved QOL. Most evidence suggested that QOL improvements were not completely attributable to weight loss.
      • However, improvements in HRQOL did not appear to be dependent solely on weight loss.
        • Blissmer B.
        • Riebe D.
        • Dye G.
        • Ruggiero L.
        • Greene G.
        • Caldwell M.
        Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects.
      • Our findings suggest QOL improvement are limited to the domains of sexual function and energy and mobility independent of the dietary approach used and independent of changes in weight and A1C.
        • Davis N.J.
        • Tomuta N.
        • Isasi C.R.
        • Leung V.
        • Wylie-Rosett J.
        Diabetes-specific quality of life after a low-carbohydrate and low-fat dietary intervention.
      Low calorie, low-fat
      • ≤ 25% of energy from fat
      • kcal restriction based on baseline weight (1,200–2,000 kcal)
      All but 1 study intervention arm endorsing calorie restriction with emphasis on fat reduction produced improved QOL. Evidence suggested that QOL improvements were mostly, but not completely, attributable to weight loss.
      • We also found significant associations between weight loss, increased aerobic fitness, and improvements in HRQOL and psychological factors, suggesting that these factors may explain, at least in part, the improved HRQOL observed in the diet and exercise interventions.
        • Imayama I.
        • Alfano C.M.
        • Kong A.
        • et al.
        Dietary weight loss and exercise interventions effects on quality of life in overweight/obese postmenopausal women: a randomized controlled trial.
      • Our findings demonstrate that improvements in HRQOL occurring across different diabetes prevention interventions in the DPP were mediated primarily by weight loss, and no significant improvement in global HRQOL occurred through intervention pathways independent of weight loss.
        • Ackermann R.T.
        • Edelstein S.L.
        • Narayan K.M.
        • et al.
        Changes in health state utilities with changes in body mass in the Diabetes Prevention Program.
      Low carbohydrate
      • < 20 g/d
      Both study intervention arms endorsing low-carbohydrate diets produced improved QOL. Evidence suggested that at least some aspect of QOL improvement was independent of weight loss.
      • Our findings suggest QOL improvement are limited to the domains of sexual function and energy and mobility independent of the dietary approach used and independent of changes in weight and A1C.
        • Davis N.J.
        • Tomuta N.
        • Isasi C.R.
        • Leung V.
        • Wylie-Rosett J.
        Diabetes-specific quality of life after a low-carbohydrate and low-fat dietary intervention.
      • Compared with a low-fat diet, a low-carbohydrate diet led to similar improvements in the physical aspects of HRQOL and greater improvements in mental aspects of HRQOL as measured by the SF-36. The greater improvement in the mental aspects of HRQOL appeared to be related more to some aspect of the low-carbohydrate diet than to the greater weight loss that occurred on this diet.
        • Yancy Jr., W.S.
        • Almirall D.
        • Maciejewski M.L.
        • Kolotkin R.L.
        • McDuffie J.R.
        • Westman E.C.
        Effects of two weight-loss diets on health-related quality of life.
      High protein
      • 40% CHO, 30% protein, 30% fat
      Evangelista et al
      • Evangelista L.S.
      • Heber D.
      • Li Z.
      • Bowerman S.
      • Hamilton M.A.
      • Fonarow G.C.
      Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study.
      reported that improvements in QOL for those consuming a high protein diet were associated with weight loss.

      The positive effects of short-term weight loss on QOL in overweight and obese individuals have been documented in the obesity literature and confirmed by data from the current study that showed improvements in overall and physical QOL at the end of the 12-week dietary intervention in which there was moderate weight loss.
      • Evangelista L.S.
      • Heber D.
      • Li Z.
      • Bowerman S.
      • Hamilton M.A.
      • Fonarow G.C.
      Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study.
      Commercial dietAll interventions endorsing a commercial weight loss program such as Weight Watchers produced improved QOL and largely suggested that QOL improvements were related to weight losses.
      • The current study's investigators demonstrated that the beneficial effects of weight loss on physical and functional QOL extend to obese breast cancer survivors; however, whether that was a result of the weight loss or the exercise that was part of the weight loss program is difficult to determine.
        • Darga L.L.
        • Magnan M.
        • Mood D.
        • Hryniuk W.M.
        • DiLaura N.M.
        • Djuric Z.
        Quality of life as a predictor of weight loss in obese, early-stage breast cancer survivors.
      • Weight strongly predicted total score and all subscale scores, with the strongest relationships for public distress, physical function, and total score.
        • Heshka S.
        • Anderson J.W.
        • Atkinson R.L.
        • et al.
        Weight loss with self-help compared with a structured commercial program: a randomized trial.
      General healthy dietAll study interventions of generally healthy diets produced improved QOL. No studies clearly indicated whether QOL improvements were independent of weight loss.
      BMI indicates body mass index; CHO, carbohydrates; HRQOL, Health-Related Quality of Life; QOL, quality of life; SF-36, Short Form–36 Health Survey.

      Discussion

      A total of 24 studies were included in this systematic review, designed to assess whether dietary intervention alone affects QOL for individuals attempting weight loss. Across these studies, the Short Form–36, a general health QOL instrument, was the most widely used. Several studies also used a disease-specific survey (eg, Impact of Weight on Quality of Life–Lite, Functional Assessment of Cancer Therapy–General, Polycystic Ovarian Syndrome Health–Related Quality of Life, and Minnesota Living with Heart Failure) to measure QOL in various populations. This review revealed that the large majority (21 of 24; 88%) of studies reported improvement in QOL over time; however, for nearly half of the studies, it was unclear whether improvement in QOL was as a result of weight loss and/or risk factor reduction rather than actual implementation of dietary changes.
      Based on the findings of this review, there is a lack of data to support whether implementing dietary change positively or negatively affects QOL independent of weight loss. Although it is widely accepted that there is no downside to encouraging generally healthy, overweight, and obese persons to eat more fruits and vegetables or eat less calories, the results of this review suggest that it remains unclear whether making dietary changes translates into improved QOL regardless of whether the individual actually loses weight. The only dietary recommendation consistently associated with improved QOL was the low-carbohydrate diet, but this was limited to only 2 studies
      • Davis N.J.
      • Tomuta N.
      • Isasi C.R.
      • Leung V.
      • Wylie-Rosett J.
      Diabetes-specific quality of life after a low-carbohydrate and low-fat dietary intervention.
      • Yancy Jr., W.S.
      • Almirall D.
      • Maciejewski M.L.
      • Kolotkin R.L.
      • McDuffie J.R.
      • Westman E.C.
      Effects of two weight-loss diets on health-related quality of life.
      Yancy et al
      • Yancy Jr., W.S.
      • Almirall D.
      • Maciejewski M.L.
      • Kolotkin R.L.
      • McDuffie J.R.
      • Westman E.C.
      Effects of two weight-loss diets on health-related quality of life.
      suggested that the allowance of unlimited consumption of certain food groups while on a low-carbohydrate diet may improve QOL in contrast to diets focused solely on calorie restriction. Because diet is linked to a range of factors, as illustrated in Figure 1, it is important to consider how making broad dietary recommendations for all individuals might affect overall QOL in both positive and negative directions. For example, attempting to adopt standard dietary recommendations such as eating more fruits and vegetables or fewer calories may have social implications by making an individual feel isolated or disconnected from his or her social circles, which may not be attempting to adopt the same recommended eating patterns. These recommendations may also have economic implications that negatively affect the QOL for those with a limited income. In contrast, adoption of a healthier dietary pattern may lead to increased personal satisfaction associated with successful implementation of a behavior change, and thus improved QOL, regardless of whether weight loss occurs. Further exploration of mechanisms influencing QOL is warranted.
      One apparent limitation for advancing research to examine the effect of diet on QOL is the lack of nutrition-specific tools for assessment. Initial work from Barr and Schumacher
      • Barr J.
      • Schumacher G.
      Using focus groups to determine what constitutes quality of life in clients receiving medical nutrition therapy: first steps in the development of a nutrition quality-of-life survey.
      • Barr J.T.
      • Schumacher G.E.
      The need for a nutrition-related quality-of-life measure.
      yielded the Nutrition Quality of Life questionnaire. However, reported use in the literature has been infrequent.
      • Lin L.P.
      • Elena W.
      • Razif S.M.
      Nutrition quality of life among female-majority Malay undergraduate students of health sciences.
      Recently, another nutrition-specific QOL tool was developed by Schunemann and colleagues
      • Schunemann H.J.
      • Sperati F.
      • Barba M.
      • et al.
      An instrument to assess quality of life in relation to nutrition: item generation, item reduction and initial validation.
      for Italian populations, but it has not been adapted or tested in other populations such as the United States. Nevertheless, statistical approaches can be employed to begin to disentangle the possible relationships between treatment effect, weight loss, and QOL in behavioral weight loss interventions, even in the absence of specific tools for measuring nutrition-related QOL.
      This study was also limited. The range of dates for included studies may have affected the QOL surveys included. A start year of 1990 was selected to coincide with the onset of the obesity epidemic and the era in which there was a marked increase in the number of behavioral weight control studies. However, new QOL instruments have been developed over the past 20 years that were not available to be used in earlier studies.
      Most studies indicated that participants in behavioral weight control studies report improved QOL after the intervention; however, there are limited published data to determine whether an independent effect of implementing dietary change on QOL exists. Evidence for the impact of diet on QOL would be strengthened by a nutrition-specific QOL tool. The effect of implementing recommended dietary changes for weight loss–seeking individuals may affect QOL through a range of domains other than weight loss or health improvement.

      Implications For Research and Practice

      The lack of evidence needed to fully understand the impact of dietary interventions on QOL has research and clinical implications that must be considered and addressed. If dietary interventions are adversely affecting QOL and this potential relationship is not being detected or reported by current research practices, barriers for successful dietary changes and maintenance of changes may not be fully understood. Statistical methodology (eg, modeling, mediation tests) can be used with current tools to begin to explore the effect of dietary changes alone on QOL. In addition, the optimal approach is to develop specific tools to accurately assess the effect of implementing dietary changes on the full spectrum of factors that influence QOL.

      Uncited tables

      Acknowledgment

      Dr. Hidalgo was funded by National Heart, Lung, and Blood Institute, University of Alabama Statistical Genetics Postdoctoral Training Program Grant 5T32HL072757-10 .

      References

        • Knowler W.C.
        • Barrett-Connor E.
        • Fowler S.E.
        • et al.
        Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin.
        N Engl J Med. 2002; 346: 393-403
        • Appel L.J.
        • Champagne C.M.
        • Harsha D.W.
        • et al.
        Effects of comprehensive lifestyle modification on blood pressure control: main results of the PREMIER clinical trial.
        JAMA. 2003; 289: 2083-2093
        • Chlebowski R.T.
        • Blackburn G.L.
        • Thomson C.A.
        • et al.
        Dietary fat reduction and breast cancer outcome: interim efficacy results from the Women's Intervention Nutrition Study.
        J Natl Cancer Inst. 2006; 98: 1767-1776
        • The WHOQOL Group
        The World Health Organization Quality of Life Assessment. Development and psychometric properties.
        Soc Sci Med. 1998; 46: 1569-1585
        • Maciejewski M.L.
        • Patrick D.L.
        • Williamson D.F.
        A structured review of randomized controlled trials of weight loss showed little improvement in health-related quality of life.
        J Clin Epidemiol. 2005; 58: 568-578
        • Fontaine K.R.
        • Barfosky I.
        Obesity and health-related quality of life.
        Obes Rev. 2001; 2: 173-182
        • Moher D.
        • Liberati A.
        • Tetzlaff J.
        • Altman D.G.
        Preferred Reporting Items for Systematic Reviews and Meta-Analyses: the PRISMA Statement.
        Ann Intern Med. 2009; 151: 264-269
        • Slim K.
        • Nini E.
        • Forestier D.
        • Kwiatkowski F.
        • Panis Y.
        • Chipponi J.
        Methodological index for non-randomized studies (minors): development and validation of a new instrument.
        ANZ J Surg. 2003; 73: 712-716
        • Blissmer B.
        • Riebe D.
        • Dye G.
        • Ruggiero L.
        • Greene G.
        • Caldwell M.
        Health-related quality of life following a clinical weight loss intervention among overweight and obese adults: intervention and 24 month follow-up effects.
        Health Qual Life Outcomes. 2006; 4: 43
        • Malone M.
        • Alger-Mayer S.A.
        • Anderson D.A.
        The lifestyle challenge program: a multidisciplinary approach to weight management.
        Ann Pharmacother. 2005; 39: 2015-2020
        • Ross K.M.
        • Milsom V.A.
        • Rickel K.A.
        • et al.
        The contributions of weight loss and increased physical fitness to improvements in health-related quality of life.
        Eat Behav. 2009; 10: 84-88
        • Evangelista L.S.
        • Heber D.
        • Li Z.
        • Bowerman S.
        • Hamilton M.A.
        • Fonarow G.C.
        Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study.
        J Cardiovasc Nurs. 2009; 24: 207-215
        • Pope L.
        • Harvey-Berino J.
        • Savage P.
        • et al.
        The impact of high-calorie-expenditure exercise on quality of life in older adults with coronary heart disease.
        J Aging Phys Act. 2011; 19: 99-116
        • Ackermann R.T.
        • Edelstein S.L.
        • Narayan K.M.
        • et al.
        Changes in health state utilities with changes in body mass in the Diabetes Prevention Program.
        Obesity (Silver Spring). 2009; 17: 2176-2181
        • Davis N.J.
        • Tomuta N.
        • Isasi C.R.
        • Leung V.
        • Wylie-Rosett J.
        Diabetes-specific quality of life after a low-carbohydrate and low-fat dietary intervention.
        Diabetes Educ. 2012; 38: 250-255
        • Heshka S.
        • Anderson J.W.
        • Atkinson R.L.
        • et al.
        Weight loss with self-help compared with a structured commercial program: a randomized trial.
        JAMA. 2003; 289: 1792-1798
        • Melanson K.J.
        • Dell'Olio J.
        • Carpenter M.R.
        • Angelopoulos T.J.
        Changes in multiple health outcomes at 12 and 24 weeks resulting from 12 weeks of exercise counseling with or without dietary counseling in obese adults.
        Nutrition. 2004; 20: 849-856
        • Rejeski W.J.
        • Focht B.C.
        • Messier S.P.
        • Morgan T.
        • Pahor M.
        • Penninx B.
        Obese, older adults with knee osteoarthritis: weight loss, exercise, and quality of life.
        Health Psychol. 2002; 21: 419-426
        • Rippe J.M.
        • Price J.M.
        • Hess S.A.
        • et al.
        Improved psychological well-being, quality of life, and health practices in moderately overweight women participating in a 12-week structured weight loss program.
        Obes Res. 1998; 6: 208-218
        • Villareal D.T.
        • Banks M.
        • Sinacore D.R.
        • Siener C.
        • Klein S.
        Effect of weight loss and exercise on frailty in obese older adults.
        Arch Intern Med. 2006; 166: 860-866
        • Villareal D.T.
        • Chode S.
        • Parimi N.
        • et al.
        Weight loss, exercise, or both and physical function in obese older adults.
        N Engl J Med. 2011; 364: 1218-1229
        • Wolf A.M.
        • Conaway M.R.
        • Crowther J.Q.
        • et al.
        Translating lifestyle intervention to practice in obese patients with type 2 diabetes: Improving Control with Activity and Nutrition (ICAN) study.
        Diabetes Care. 2004; 27: 1570-1576
        • Womble L.G.
        • Wadden T.A.
        • McGuckin B.G.
        • Sargent S.L.
        • Rothman R.A.
        • Krauthamer-Ewing E.S.
        A randomized controlled trial of a commercial internet weight loss program.
        Obes Res. 2004; 12: 1011-1018
        • Yancy Jr., W.S.
        • Almirall D.
        • Maciejewski M.L.
        • Kolotkin R.L.
        • McDuffie J.R.
        • Westman E.C.
        Effects of two weight-loss diets on health-related quality of life.
        Qual Life Res. 2009; 18: 281-289
        • Williamson D.A.
        • Rejeski J.
        • Lang W.
        • et al.
        Impact of a weight management program on health-related quality of life in overweight adults with type 2 diabetes.
        Arch Intern Med. 2009; 169: 163-171
        • Fontaine K.R.
        • Barofsky I.
        • Andersen R.E.
        • et al.
        Impact of weight loss on health-related quality of life.
        Qual Life Res. 1999; 8: 275-277
        • Imayama I.
        • Alfano C.M.
        • Kong A.
        • et al.
        Dietary weight loss and exercise interventions effects on quality of life in overweight/obese postmenopausal women: a randomized controlled trial.
        Int J Behav Nutr Phys Act. 2011; 8: 118
        • Ware J.E.
        • Kosinski M.
        • Keller S.D.
        SF-36 Physical and Mental Health Summary Scales: A User's Manual.
        New England Medical Center, Boston, MA1994
        • Barham K.
        • West S.
        • Trief P.
        • Morrow C.
        • Wade M.
        • Weinstock R.S.
        Diabetes prevention and control in the workplace: a pilot project for county employees.
        J Public Health Manag Pract. 2011; 17: 233-241
        • Kennedy B.M.
        • Paeratakul S.
        • Champagne C.M.
        • et al.
        A pilot church-based weight loss program for African-American adults using church members as health educators: a comparison of individual and group intervention.
        Ethn Dis. 2005; 15: 373-378
        • Kolotkin R.L.
        • Head S.
        • Hamilton M.
        • Tse C.K.
        Assessing impact of weight on quality of life.
        Obes Res. 1995; 3: 49-56
        • Darga L.L.
        • Magnan M.
        • Mood D.
        • Hryniuk W.M.
        • DiLaura N.M.
        • Djuric Z.
        Quality of life as a predictor of weight loss in obese, early-stage breast cancer survivors.
        Oncol Nurs Forum. 2007; 34: 86-92
        • Ladson G.
        • Dodson W.C.
        • Sweet S.D.
        • et al.
        The effects of metformin with lifestyle therapy in polycystic ovary syndrome: a randomized double-blind study.
        Fertil Steril. 2011; 95: 1059-1066.e1–7
        • von Gruenigen V.E.
        • Gibbons H.E.
        • Kavanagh M.B.
        • Janata J.W.
        • Lerner E.
        • Courneya K.S.
        A randomized trial of a lifestyle intervention in obese endometrial cancer survivors: quality of life outcomes and mediators of behavior change.
        Health Qual Life Outcomes. 2009; 7: 17
        • Barr J.
        • Schumacher G.
        Using focus groups to determine what constitutes quality of life in clients receiving medical nutrition therapy: first steps in the development of a nutrition quality-of-life survey.
        J Am Diet Assoc. 2003; 103: 844-851
        • Barr J.T.
        • Schumacher G.E.
        The need for a nutrition-related quality-of-life measure.
        J Am Diet Assoc. 2003; 103: 177-180
        • Lin L.P.
        • Elena W.
        • Razif S.M.
        Nutrition quality of life among female-majority Malay undergraduate students of health sciences.
        Malays J Med Sci. 2012; 19: 37-49
        • Schunemann H.J.
        • Sperati F.
        • Barba M.
        • et al.
        An instrument to assess quality of life in relation to nutrition: item generation, item reduction and initial validation.
        Health Qual Life Outcomes. 2010; 8: 26