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Adult Weight Management

AWM: Meal Replacements (2006)

Citation:

Rothacker DQ, Staniszewski BA, Ellis PK.  Liquid meal replacement vs traditional food:  a potential model for women who cannot maintain eating habit change.  J Am Diet Assoc 2001; 101(3): 345-347.

 
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 compare the effects on body weight and body composition of 2 diet plans similar in macronutrients followed over a 1-year period.
Inclusion Criteria:
Healthy but overweight women, aged 18 - 55 years, BMI 25 - 32, wanting to maintain 20 - 40 lb weight loss but with difficulty adhering to changed eating habits.
Exclusion Criteria:
No significant health conditions.
Description of Study Protocol:

Recruitment

Recruited via newspaper advertisement.

Design

Randomized Controlled Trial.

Blinding used (if applicable)

Not blinded.

Intervention (if applicable)

Randomized to 1 of 2 diets:  one plan incorporated portion-controlled premeasured meal replacement shake powder to replace 1 or more meals per day, the other plan followed a more traditional low-fat, low-energy diet.  Both plans provided 1200 kcals/day with 55% kcals from carbohydrate, 15% kcals from protein, and 30% kcals from fat.  Exercise was not monitored. 

Statistical Analysis

For both groups, significance levels of mean changes from baseline were assessed by paired t test.  The differences between treatment groups at baseline, week 12 and week 52 were assessed by independent tests.  The means are presented with confidence intervals and standard deviations.  All tests are 2-tailed.

Data Collection Summary:

Timing of Measurements

Lean body mass, body fat percentage, and fat mass assessments were made at baseline, 3 months and 1 year.  All measurements made after overnight fast, without shoes, and with subjects in light clothing by same investigator.  All subjects came once a month to report any medications taken or side effects and to obtain free meal replacement powder packets (had to purchase skim milk).

Dependent Variables

  • Body weight measured on balance beam scale 
  • Body composition through bioelectric impedance  

Independent Variables

  • 1200 kcal dietary intervention.  All participants were initially provided with several days worth of groceries.  Women following traditional low-fat, low-energy diet received literature containing instructions for weight loss and healthful eating, including sample diets and exchange lists.  Meal replacement group was instructed to replace 3 meals per day with milk-based meal replacement shake (220 kcals, 1.5 g total fat, 5 g fiber, 15 - 19 g protein). 

Control Variables

 

Description of Actual Data Sample:

Initial N: 75 women enrolled

Attrition (final N):  64 completed all 52 weeks (15% dropout rate).  Dropouts were evenly distributed, 6 meal replacements, 5 traditional food.  3 subjects were eliminated as their BMI was < 25.

Age:  Both treatment groups were similar at baseline for age.  Meal replacements:  36.1 +/- 7.2 years, traditional foods:  37.5 +/- 6.2 years. 

Ethnicity: Not mentioned.

Other relevant demographics:  Both treatment groups were similar at baseline for BMI.  Meal replacements:  28.6 +/- 1.7, traditional foods:  29.2 +/- 1.7. 

Anthropometrics:  Groups were the same with respect to age and BMI.

Location:  New Jersey 

 

Summary of Results:

 

Baseline Week 12 Treatment Difference P-value Week 52

Treatment Difference P-value

Weight - MR 75.2 +/- 6.9 69.2 +/- 6.4 68.9 +/- 7.7
Weight - TF 77.5 +/- 7.5 73.7 +/- 7.6 76.2 +/- 9.4
Weight Change - MR -6.3 +/- 0.6 0.008 -6.4 +/- 0.9 0.000
Weight Change - TF -3.8 +/- 0.5 -1.2 +/- 0.7
Fat Mass - MR 32.8 +/- 5.9 26.8 +/- 5.0 27.5 +/- 6.7
Fat Mass - TF 34.5 +/- 6.2 30.3 +/- 6.2 33.9 +/- 7.9
Fat Mass Change - MR -6.0 +/- 0.8 0.050 -5.3 +/- 0.9 0.002
Fat Mass Change - TF -3.9 +/- 0.6 -0.9 +/- 0.9
Fat % - MR 44.0 +/- 5.0 38.9 +/- 4.8 39.7 +/- 5.9
Fat % - TF 44.8 +/- 5.2 41.7 +/- 5.6 44.5 +/- 6.8
Fat % Change - MR -5.1 +/- 0.7 0.060 -4.3 +/- 0.9 0.002
Fat % Change - TF -3.1 +/- 0.7 -0.3 +/- 0.8
Lean Body Mass - MR 41.4 +/- 4.0 41.8 +/- 3.9 40.9 +/- 3.8
Lean Body Mass - TF 42.2 +/- 4.5 42.4 +/- 4.7 41.6 +/- 5.0
LBM Change - MR

 

-0.4 +/- 0.3

0.588 0.5 +/- 0.3

0.782

LBM Change - TF

 

-0.3 +/- 0.4

0.6 +/- 0.5

 

Other Findings

At 3 months, subjects from both groups had significant reductions from baseline weight and body fat without loss of lean body mass.  There were no significant differences in fat reductions.

After 1 year, the meal replacement group maintained their initial (week 12) weight/fat loss, whereas the traditional food group regained most of their initial weight and fat losses.

Treatment differences were significant for weight (P < 0.001), fat mass (P < 0.002), and percent fat (P < 0.002), but not lean body mass.   

Author Conclusion:

The results of this 1-year study indicate that meal replacements may be a useful tool for long-term weight and fat control for patients unable to alter their eating habits.  If past attempts have shown that your patient is likely to resort to previous eating habits after dieting, consider including that behavior when developing their diet plan.

Funding Source:
Reviewer Comments:
Exercise was not monitored.  Low dropout rate after 1 year (15%).
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) ???
  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? 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? Yes
  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? No
  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? 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? 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)? 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? 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