AWM: Nutrient Adequacy and Caloric Restriction (2013)


Ma Y, Pagoto SL, Griffith JA, Merriam PA, Ockene IS, Hafner AR, Olendzki BC. A dietary quality comparison of popular weight-loss plans. J Am Diet Assoc. 2007; 107 (10): 1,786-1,791.

PubMed ID: 17904938
Study Design:
Descriptive Study
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
  • The purpose of this study was to compare popular weight-loss plans' dietary quality as well as other nutrients associated with reduced CVD
  • Given that obesity is a risk factor for CVD, the optimal weight-loss plan will facilitate weight loss and CVD risk reduction.
Inclusion Criteria:
  • The criterion for determining which weight-loss plans were the most popular was their status on the New York Times Bestseller list
  • Weight Watchers and the 2005 Food Guide Pyramid plan were included because they are the largest commercial weight-loss plan and the current government recommendation, respectively.
Exclusion Criteria:

Not described.

Description of Study Protocol:


Not applicable.


Descriptive study.

Statistical Analysis

  • Descriptive statistics such as mean ±standard deviation were used to summarize the plans' AHEI and nutrient scores
  • Analysis of variance was used to compare AHEI scores and components of the AHEI and energy intake; percentage energy from carbohydrate, fat, protein, saturated and monounsaturated fat; N-3 fatty acids, total fiber and sodium
  • P-values from omnibus test were reported
  • For each AHEI score, follow-up multiple comparisons with a Bonferroni correction were conducted
  • Because total energy was different among the plans, the AHEI scores adjusted for energy content were also compared.
Data Collection Summary:

Timing of Measurements

Not applicable.

Dependent Variables

  • Dietary quality measured by the Alternate Healthy Eating Index (AHEI): The AHEI isolates dietary components that are most strongly linked to CVD risk reduction and was developed to improve upon the Healthy Eating Index (HEI)
  • The AHEI has nine components for evaluating and determining dietary quality including fruit, vegetables, nuts, soy, ratio of white to red meat, cereal fiber, trans fat, ratio of polyunsaturated to saturated fat, alcohol and duration of multivitamin use
  • Seven of the nine AHEI components were used to evaluate or calculate the AHEI score for each plan. Duration of multivitamin use and daily alcohol intake were not used because neither were addressed in the diet book meal plans.
  • Each component received a score from zero to 10, with 10 being the best and zero being the worst.

Independent Variables

  • Meal plans were taken directly from books or websites and the analyses assumed that dieters are perfectly adherent to dietary recommendations
  • Sample menus from seven days were entered into the Nutrition Data System for Research software, version 2006, Nutrition Coordinating Center, Minneapolis, MN
  • Nutrient values including total energy, percentage energy from carbohydrate, fat and protein; number of servings of vegetables, fruits, nuts, soy, meat and cereal fiber were analyzed using the Nutrition Data System for Research software.
Description of Actual Data Sample:
  • Initial N: Popular weight loss plans were evaluated including the New Glucose Revolution, Weight Watchers, Atkins, South Beach, Zone, 2005 Food Guide Pyramid and the Ornish diet.
  • Attrition (final N): As above
  • Age: Not applicable
  • Ethnicity: Not applicable
  • Other relevant demographics: Not applicable
  • Anthropometrics: Not applicable
  • Location: Massachusetts.
Summary of Results:

Key Findings

  • The AHEI scores ordered from the highest to lowest plan were:
    1. Ornish (score, 64.6; 1,739±144kcal per day)
    2. Weight Watchers high-carbohydrate (score, 57.4; 1,204±104kcal per day)
    3. The New Glucose Revolution (score, 57.2; 1,729±133kcal per day)
    4. South Beach/Phase 2 (score, 50.7; 1,272±263kcal per day)
    5. Zone (score, 49.8; 1,025±122kcal per day)
    6. 2005 Food Guide Pyramid (score, 48.7; 1,946±200kcal per day)
    7. Weight Watchers high-protein (score, 47.3; 1,118±79kcal per day)
    8. Atkins/100g carbohydrate (score, 46; 1,858±253kcal per day)
    9. The South Beach Phase 3 (score, 45.6; 1,404±273kcal per day)
    10. Atkins/45g carbohydrate (score, 42.3; 1,547±218kcal per day).
  • The omnibus test revealed a statistically significant difference in AHEI scores among plans (P<0.01)
  • The Ornish Plan was significantly different from the Atkins/100g carbohydrate (P=0.007), Atkins/45g carbohydrate (P=0.0004), South Beach/Phase 3 (P=0.005) and Weight Watchers high-protein plans (P=0.02). All other comparisons were not statistically different.
  • In this analysis, the highest adjusted AHEI was Ornish (score, 61.9) and the Atkins/45g carbohydrate plan (score, 41.6) remained the lowest.
Author Conclusion:

None of the popular weight-loss plans studied achieved a perfect alternate healthy eating index (AHEI) score, but the Ornish, Weight Watchers high-carbohydrate and New Glucose Revolution plans were among the best performers using the AHEI and traditional dietary quality assessments.

Funding Source:
University/Hospital: Diabetes Endocrinology Research Center at the University of Massachusetts Medical School
Reviewer Comments:

This study had several limitations

  • The analyses assumed perfect adherence to dietary recommendations: Future research should assess the quality of weight-loss plans as they are carried out
  • Only eight popular weight loss plans were analyzed
  • Dietary supplements were not included in the analyses
  • The AHEI has not been validated for chronic disease in general.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? No
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? N/A
  2.4. Were the subjects/patients a representative sample of the relevant population? No
3. Were study groups comparable? N/A
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) N/A
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? N/A
  4.1. Were follow-up methods described and the same for all groups? N/A
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) N/A
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? N/A
  4.4. Were reasons for withdrawals similar across groups? N/A
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) N/A
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? ???
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? N/A
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? No
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? Yes
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? ???
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? N/A
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? ???
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? N/A
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? N/A
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes