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Adult Weight Management

AWM: Meal Replacements (2006)

Citation:

Allison DB, Gadbury G, Schwartz LG, Murugesan R, Kraker JL, Heshka S, Fontaine KR, Heymsfield SB.  A novel soy-based meal replacement formula for weight loss among obese individuals:  a randomized controlled clinical trial.  Eur J Clin Nutr 2003; 57(4): 514-522. 

PubMed ID: 12700612
 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To assess the efficacy and safety of a low calorie soy-based meal replacement program for the treatment of obesity. 
Inclusion Criteria:
Obese (BMI 28 - 41) volunteers aged 35 - 65 years.  Prior to participation and acceptance into the program, subjects were deemed medically fit for safe weight loss through a physical examination.
Exclusion Criteria:
Weight loss > 5 kg in the past 3 months, use of weight loss medication within the past 6 weeks, scores above the 90th percentile on the Brief Symptom Inventory (a screening measure of general psychological functioning), presence of disease not believed to be at least partially the result of obesity and treatable by weight reduction, medical or psychological contraindications as determined by study investigators, or known hypersensitivity to any of the ingredients of the formula, including but not limited to, soy protein.   
Description of Study Protocol:

Recruitment

Methods not specified.

Design

12-week prospective randomized controlled clinical trial.

Blinding used (if applicable)

Not blinded.

Intervention (if applicable)

Participants randomized by computer-generated pseudo random numbers to either Scan Diet meal replacement treatment group (n=50, 240 g day, 1185 kcal/day) or control group (n=50).  Both groups at baseline received a single dietary counseling session and a pamphlet describing weight loss practices.  The treatment group was instructed to follow a daily diet of 5 Scan Diet shakes, 4 exchanges of fruit, 4 exchanges of vegetables and 1 fat exchange.  They were also given a copy of the Nutricia Scan Diet Meal Plan booklet as well as a copy of ADA 1995 Exchange Lists for Weight Management.  The control group was also given the 1995 Exchange Lists and instructed to follow 1200 kcal meal plan. 

Statistical Analysis

To calculate power, we assumed a within-group weight loss standard deviation of ~3.5 kg over a 12 week period.  Under these assumptions, 60 complete subjects provde over 80% power to reject the null hypothesis at a two-tailed alpha of 0.05 if the between-group difference is as small as 2.7 kg.  Using a conservative estimate of a 40% post-randomization attrition rate, a total of 100 subjects were randomized into the study.  The primary analysis was an intention-to-treat analysis (data from all subjects were analyzed regardless of whether those subjects complied with or remained in treatment).  Missing data due to dropouts were handled via multiple imputation (the missing data points were computed from a probability model obtained from observed values).  Analyses were also conducted on the completers only.  Data were analyzed using ANCOVA at each subsequent visit.  Change from baseline of a subject's response was the dependent variable and the corresponding baseline response was a covariate.  We did not detect any treatment x baseline interactions, nor did we find other covariates that were significant in explaining the variation in the dependent variable.  We also analyzed changes in cholesterol and its sub-fractions using a linear regression model that included corresponding weight change as a covariatew, the purpose being to determine if there were cholesterol reductions after adjusting for changes in weight.

Data Collection Summary:

Timing of Measurements

Each patient was followed up at 4 week intervals for 12 weeks or until dropout.  They were seen a total of 4 times including baseline.  At each visit, subjects had blood samples drawn, anthropometric measures, blood pressure and psychological wellness assessments.  Laboratory assessment included complete blood count and serum lipids.

Dependent Variables

  • Body weight measured within 0.1 kg using a standardized calibrated scale
  • Height measured within 0.1 cm using a wall-mounted stadiometer 
  • Body fat measured through TANITA bio-impedance analyzer
  • Waist circumference taken with non-distensible tape measure according to published guidelines
  • Blood pressure measured after 5 minute rest using standard mercury sphygmomanometer and appropriately sized cuffs according to AHA guidelines 
  • Fasting blood samples analyzed by a commercial lab 
  • Side effects and adverse effects assessed by standardized interview / questionnaire, the Monitoring of Side Effects Scale (MOSES)

Independent Variables

  • Dietary intervention:  at each visit, subjects in treatment group were checked for compliance to encourage and monitor use of the product, and were supplied additional meal replacements.  Compliance was checked through interview and counting of meal replacement packets.  The control group was not checked for compliance.  Neither group was asked to keep food records. 

Control Variables

 

Description of Actual Data Sample:

Initial N: 120 subjects screened and 100 overweight / obese subjects (20 men, 80 women) randomized.

Attrition (final N):  74 subjects completed the trial.

Age:  Treatment group:  mean age 50.4 +/- 8.9 years, controls:  mean age 50.0 +/- 8.0 years. 

Ethnicity:  Not mentioned. 

Other relevant demographics:  BMI treatment group:  35.1 +/- 7.9, controls:  33.5 +/- 3.5 

Anthropometrics:  Differences between groups on measured baseline characteristics were not statistically significant.

Location:  University of Alabama 

 

Summary of Results:

 

Period Treatment Group Controls P Value
Weight (kg) 4 weeks -3.5 +/- 3.8 -2.7 +/- 4.5 0.379
8 weeks -5.5 +/- 5.7 -3.0 +/- 4.9 0.058
12 weeks -7.0 +/- 4.6 -2.9 +/- 3.3 0.001
Body Fat Mass (%) 4 weeks -0.5 +/- 3.0 -0.3 +/- 2.0 0.743
8 weeks -0.6 +/- 3.5 -0.5 +/- 4.2 0.864
12 weeks -1.5 +/- 3.6 -0.2 +/- 4.8 0.255
Fat Mass (kg) 4 weeks -1.8 +/- 3.3 -1.5 +/- 3.0 0.377
8 weeks -3.0 +/- 4.1 -1.7 +/- 3.9 0.011
12 weeks -4.3 +/- 4.0 -1.4 +/- 4.8 0.003
Waist Circumference (cm) 4 weeks -3.2 +/- 4.0 -2.9 +/- 4.0 0.553
8 weeks -5.4 +/- 4.5 -3.9 +/- 8.3 0.324
12 weeks -6.0 +/- 4.2 -2.9 +/- 3.7 0.003
Total Cholesterol (mg/dl) 4 weeks -35.5 +/- 36.8 -13.1 +/- 27.8 0.002
8 weeks -30.8 +/- 23.0 -10.6 +/- 20.4 0.0001
12 weeks

-22.5 +/- 30.2

-6.8 +/- 24.7

0.013

LDL Cholesterol (mg/dl) 4 weeks -32.9 +/- 23.0 -7.7 +/- 20.4 <0.0001
8 weeks -24.8 +/- 22.5 -8.3 +/- 18.1 <0.0001
12 weeks -21.2 +/- 23.5 -7.1 +/- 19.1 0.009
HDL Cholesterol (mg/dl) 4 weeks -4.6 +/- 8.7 -1.5 +/- 7.0 0.062
8 weeks -4.4 +/- 8.1 -1.4 +/- 6.6 0.055
12 weeks -1.5 +/- 7.8 -0.5 +/- 10.6 0.657
Diastolic BP (mm Hg) 4 weeks -2.0 +/- 8.2 0.8 +/- 7.7 0.094
8 weeks -1.1 +/- 9.4 0.7 +/- 7.3 0.336
12 weeks -1.3 +/- 11.0 0.9 +/- 6.6 0.246
Systolic BP (mm Hg) 4 weeks -1.4 +/- 12.4 -3.0 +/- 13.5 0.570
8 weeks -0.3 +/- 10.4 -0.8 +/- 12.4 0.858
12 weeks

-4.8 +/- 28.4

-1.5 +/- 12.3

0.527

Other Findings

By intent-to-treat analysis, the treatment group lost significantly more weight than the control group (7.00 vs 2.90 kg; P < 0.001) and had a greater change in total (22.5 vs 6.8 mg/dl, P = 0.013) and LDL cholesterol (21.2 vs 7.1 mg/dl, P < 0.009).

Among completers only, the treatment group again lost more weight (7.1 kg, n = 37 vs 2.9 kg, n = 37, P = 0.0001) and had a greater reduction in total cholesterol (26.1 mg/dl, n = 37 vs 6.7 mg/dl, P = 0.0012) and a greater change in LDL cholesterol (21.6 vs 5.5 mg/dl, P = 0.0025).

For any given degree of weight loss, the reduction in LDL cholesterol was significantly greater in the treatment group.

Treatment was well tolerated and no serious side effects were detected.

 

Author Conclusion:
In conclusion, use of this soy protein meal replacement formula was effective in lowering body weight, fat mass and in reducing LDL cholesterol beyond what could be expected given the weight lost.
Funding Source:
University/Hospital: University of Alabama, Columbia University, University of Missouri at Rolla Rolla, John Hopkins
Reviewer Comments:
Compliance not checked in control group.  26% dropout rate after only 12 weeks.  Funded by NutriPharma.
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? 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? ???
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.) Yes
  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? ???
  4.1. Were follow-up methods described and the same for all groups? ???
  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%.) No
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? ???
  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? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  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.) No
  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? 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? ???
  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? 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)? Yes
  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? ???
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? ???