Adult Weight Management

AWM: Meal Replacements (2006)

Citation:

Heber D, Ashley JM, Wang HJ, Elashoff RM.  Clinical evaluation of a minimal intervention meal replacement regimen for weight reduction.  J Am Coll Nutr 1994; 13(6): 608-614.

 
Study Design:
Non-Randomized Controlled Trial
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To evaluate the hypothesis that continued use of a meal replacement drink as part of a low-fat diet will result in long-term maintenance following an initial active weight loss period, and to assess the degree of weight loss, to assess changes in plasma lipids, and to evaluate patient adherence to the weight loss regimen through drop-out rates and weight loss following the initial 12-week treatment.
Inclusion Criteria:
Mildly obese subjects.
Exclusion Criteria:
Not mentioned.
Description of Study Protocol:

Recruitment

Recruited at 6 centers experienced in recruiting patients for pharmaceutical trials.

Design

Nonrandomized Clinical Trial.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Ultra Slim Fast shake for 2 meals/day for 12 weeks of weight loss, shake for 1 meal/day in weight maintenance.

Statistical Analysis

Statistical analyses were carried out using standard descriptive statistics and correlational analyses to assess the relationship of changes in measured variables vs. weight.

Data Collection Summary:

Timing of Measurements

Phase 1:  weekly follow-up visits carried out by non-physician personnel for weight management, distribution of product, and completion of subjective questionnaire for 12 weeks.  Phase 2:  followed biweekly.

Dependent Variables

  • Body weight measured using calibrated doctor's scale accurate to 0.2 lbs
  • Plasma samples drawn in fasting state were analyzed using enzymatic assays for cholesterol, triglycerides, and HDL-cholesterol
  • LDL-cholesterol calculated using Friedewald's equation

Independent Variables

  • For weight loss: Ultra Slim Fast powder with skim or 1% milk for 2 meals daily and a snack providing 660 kcal/day.  Also instructed to eat low-fat lunch or dinner, bringing total intake to 1000-1200 kcal/day.  For weight maintenance:  Ultra Slim Fast shake for 1 meal/day.  Subjects given information on dieting through package insert.  Weekly $25 payments and follow-up used to motivate continued participation.  Clinics were also compensated for retaining subjects.  Subjects were judged noncompliant for missing visits, not using the product and gaining weight and were excluded from analysis.

Control Variables

 

Description of Actual Data Sample:

Initial N: 301 subjects (71 male, 230 female)

Attrition (final N):  273 completed (91%) 12 weeks of study (206 female, 67 male).  At 116 weeks, 133 of 238 (97 females, 36 males) remained in the study (44% dropout rate between weeks 12 - 116.

Age:  Males:  mean age 38.7 years, females:  mean age 38.3 years 

Ethnicity:  At baseline:  274 Caucasian, 16 African American, 10 Hispanic, 1 Other 

Other relevant demographics:  Males:  119% average IBW, females:  122% average IBW

Anthropometrics:  

Location:  Sites in New York, Ohio, Florida, Alabama, Texas and Utah 

 

Summary of Results:

 

Time Period N Weight Change (lbs)
Females, weeks 12-38 143 -1.6 +/- 5.9
Females, weeks 38-64 103 1.3 +/- 3.8
Females, weeks 64-90 107 3.1 +/- 4.0
Females, weeks 90-116 97 2.3 +/- 3.8
Males, weeks 12-38 58 1.7 +/- 4.9
Males, weeks 38-64 45 1.1 +/- 4.7

Males, weeks 64-90

40

3.3 +/- 5.2

Males, weeks 90-116

36

2.4 +/- 5.0

Other Findings

At 12 weeks, weight loss in men was 18.6 +/- 7.0 lbs, and in women was 14.0 +/- 6.5 lbs.

At 116 weeks, average weight loss from baseline was 13.6 +/- 10.5 lb in females and 14.0 +/- 10.5 lb in males.

While the men did not lose significantly more weight after 12 weeks, women lost significant weight between weeks 12 - 24.

No statistical difference between subjects who completed 1 year of study and those who did not with respect to previous dieting, weight lost on past diets, methods of weight control, ability to keep weight off, baseline weight, height, BMI or gender.

Subjects remaining on study were older than excluded subjects or dropouts (40.9 +/- 8.3 vs 36.4 +/- 9.2 years, p < 0.05).

Married subjects were more likely to remain on the study than separated or divorced subjects (p = 0.05).

Non-Caucasian participants more likely to drop out (p = 0.02).

Changes in total cholesterol correlated with the amount of 12-week weight loss in women (n=161, r = 0.26, p < 0.01), while in men there was a similar correlation at 3 weeks (n=41, r = 0.34, p < 0.05) and 6 weeks (n=49, r = 0.31, p < 0.05) but not at 12 weeks. 

 

Author Conclusion:
The meal replacement and low fat diet followed by subjects in this study appeared to be safe and effective in treating mild to moderate obesity over a 12 week period.  The weight loss observed (approximately 10% of body weight) is significant and has been associated with important health benefits particularly for patients with hypertension and non-insulin dependent diabetes.  The potential advantages of using meal replacements for mild obesity include wide availability to aid compliance, low cost and minimal professional intervention.
Funding Source:
Government: NIH
Industry:
Slim-Fast Foods
University/Hospital: UCLA
Reviewer Comments:

Large dropout rate over the long term.  Statistics not highly sophisticated.

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? ???
  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? No
  2.2. Were criteria applied equally to all study groups? No
  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? ???
3. Were study groups comparable? ???
  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? ???
  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? 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%.) 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? 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? ???
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? No
  6.6. Were extra or unplanned treatments described? No
  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? 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? No
  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? ???
  8.1. Were statistical analyses adequately described and the results reported appropriately? ???
  8.2. Were correct statistical tests used and assumptions of test not violated? ???
  8.3. Were statistics reported with levels of significance and/or confidence intervals? ???
  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? ???
  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