MNT: Effectiveness of MNT for Obesity (2009)


Eilat-Adar S, Eldar M, Goldbourt U. Association of intentional changes in body weight with coronary heart disease event rates in overweight subjects who have an additional coronary risk factor. Am J Epidemiol 2005; 161: 352-358.

PubMed ID: 15692079
Study Design:
Cohort Study
B - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

To determine whether weight loss or weight loss rate among overweight people with CHD risk is associated with the incidence of CHD or mortality. 

Inclusion Criteria:
  • Outpatients
  • Aged 50 to 75 years
  • BMI of 27kg/m2 or greater
  • Without CHD or cancer but with at least one risk factor for CHD in addition to overweight, defined as diabetes, hypertension, dyslipidemia, CHD in a first-degree relative under the age of 60 years; diabetes in a first-degree relative; cerebrovascular accident in a first-degree relative, hyperuricemia and BMI greater than 35kg/m2. 
Exclusion Criteria:

Diagnosis of cancer

Description of Study Protocol:


In 1994-2001, the authors conducted an observational study of intentional weight loss as related to CHD incidence among patients recruited from 30 Maccabi Health Services nutritional counseling clinics in central Israel who received nutritional counseling from a dietitian to support the medical recommendation to lose weight.


Cohort Study 

Blinding used 

Adjudicators of coronary event status were blinded to weight loss status


  • Weight loss under nutritional supervision for at least 10 weeks 
  • Nutritional supervision implied regular visits with a clinical nutritionist
  • The supervision process included two to five meetings during the first three months and at least one visit every three months, up to 24 months for all participants
  • Nutritionists were graduates of the Hebrew University Faculty of Agriculture who were subsequently trained in seminars in the Maccabi Health Services in central Israel
  • Diets for overweight subjects were based on the National Cholesterol Education Program, American Diabetes Association or American Dietetic Association guidelines and considered the person's lifestyle.

Statistical Analysis 

  • 2,000 subjects were targeted for nutritional supervision, so that with 25% failing to lose weight, this sample size would provide ample statistical power to determine the CHD incidence
  • Incidence rates for CHD were calculated after adjustment for diabetes, hypertension and hypercholesterolemia
  • Weight loss was repeatedly calculated during the follow-up period and was divided into quartiles according to follow-up period
  • Association of weight change with morbidity was estimated by using multivariate analysis adjusted for the following possible confounders: Age, sex, diabetes mellitus, hypertension, smoking, hypercholesterolemia, initial BMI and reported physical activity
  • Alcohol consumption was not included as a confounder since 91% did not consume alcohol and 98% reported consuming less than one glass per day
  • Logistic regression was used to calculate the odds ratio for CHD incidence using two different analyses.
Data Collection Summary:

Timing of Measurements

Outcomes were documented over four years by repeated weight measurements and by medical record verification. The follow-up extended from January 1, 1996 until November 30, 2001.

Dependent Variables

Coronary endpoints including International Classification of Diseases, Ninth Revision codes 402-404.9, 410-414.9 or percutaneous transluminal coronary angioplasty, coronary artery bypass graft, initiation of nitrate therapy or death from all causes (except cancer).

Independent Variables

Weight loss under nutritional supervision for at least 10 weeks

Control Variables

  • Age
  • Sex
  • Diabetes mellitus
  • Hypertension
  • Smoking
  • Hypercholesterolemia
  • Initial BMI
  • Reported physical activity.
Description of Actual Data Sample:

Initial N 

2,528 questionnaires collected, 125 were initially excluded due to dieting before January 1, 1994, less than 10 weeks on the diet and duplicate coding. Data analysis was carried out on 2,403 questionnaires and 409 cancer patients were excluded. Of remaining 1,994 questionnaires, 229 had preexisting CHD, 62 patients had CHD codes and 25 had a coronary event within two months of starting the diet and were excluded. Nine were lost to follow-up.

Attrition (final N) 

Final data analysis carried out on 1,669 subjects


Aged 50 - 75 years


Not described

Other relevant demographics





Summary of Results:


Variables Number Odds Ratio 95% Confidence Interval
Diabetics 282 0.57 0.29, 1.14
Non-diabetics 659 0.70 0.58, 0.85
Subjects whose initial BMI was less than 30 318 0.46 0.23, 0.94
Subjects whose initial BMI was more than 30 623 0.57 0.33, 0.96
Men 356 0.57 0.32, 0.99
Women 585 0.46 0.24, 0.88

Other Findings

  • Mean initial BMI was 32.3±4.3kg/m2
  • Mean nutritional follow-up time was 7.6±4.9 months (range 10 weeks to 25.7 months)
  • Mean weight loss after six months on the diet was 5.0±4.3kg (between 28.9kg weight loss and 9.3kg weight gain)
  • Mean follow-up from the beginning of dietary counseling until a CHD event, death or the end of follow-up was 4.0±1.5 years (range two to 98 months) 
  • Among 1,669 patients, 224 (13.4%) incidents of CHD were recorded
  • For subjects who underwent at least six months of dietetic counseling, the risk-factor-adjusted odds ratio for CHD incidence associated with a weight loss of 4.5kg (the median level of weight loss) was 0.57 (95% confidence interval: 0.39, 0.84).
Author Conclusion:

In the current study, the largest known on this subject to date, a four-year lower CHD morbidity rate was found for subjects losing more than 4.5kg during a six-month diet. Subjects aged 50 to 75 years with a BMI of at least 27kg/m2 and at least one additional coronary risk factor should be referred for dietetic supervision.

Funding Source:
Danone-Strauss Research Grant
Food Company:
University/Hospital: Tel Aviv University Research Fund
Reviewer Comments:

Large number of subjects and long length of follow-up. Authors note the following limitations:

  • Waist-to-hip ratio not routinely measured
  • Weight reduction alone cannot be ascertained as the sole factor underlying lower CHD incidence.
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? Yes
  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? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  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? Yes
  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? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  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%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  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? Yes
  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.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? Yes
  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? Yes
  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? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? Yes
  6.6. Were extra or unplanned treatments described? N/A
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? N/A
  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? Yes
  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? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  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? N/A
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)? Yes
  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? Yes
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