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MNT: Weight Management (2015)

Citation:
Anderson J, Reynolds L, Bush H, Rinsky J, Washnock C. Effect of a behavioral/nutritional intervention program on weight loss in obese adults: a randomized controlled trial. Postgraduate Medicine, 2011; 123: 205-213. PubMed ID: 21904103
 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
  • The primary purpose of this study was to compare the effects of a standardized behavioral intervention using meal replacements, fruits and vegetables (MR-FV) and increased physical activity with a usual-care intervention (C) on change in body weight
  • Additional objectives were to assess side effects, behavioral patterns and risk factors for obese individuals.
Inclusion Criteria:
Subjects were included if:
  • They were between 20 years and 65 years old
  • BMI was 30kg/m2 to 39.9kg/m2
  • They demonstrated motivation to lose weight
  • They were not pregnant or planning to become pregnant during the study period
  • They could read and write English at a sufficient level
  • They provided signed consent prior to beginning of study.
Exclusion Criteria:
Subjects were excluded from the study if they:
  • Had known allergies to ingredients in the meal replacements (MRs)
  • Currently or had recently participated in any other clinical trial
  • Had lost or gained more than five pounds or participated in a structured weight loss program during the previous three months
  • Currently were using weight loss medications or supplements
  • Were using other medications known to affect body weight
  • They had a surgical intervention for treatment of obesity
  • Were diagnosed with diabetes or had fasting plasma glucose of more than 126mg per dL
  • Were using anticoagulants or oxcarbazepine.
Description of Study Protocol:

Recruitment
Subjects were recruited from the community through a commercial program provided at a university medical center.

Design

  • In this 24-week randomized trial, subjects were randomly assigned to either a control group receiving usual care or to an intervention group
  • In the control group, at baseline subjects received individual counseling sessions with a Registered Dietitian and were counseled to consume an energy-restricted diet providing 30% of calories from fat, 50% from carbohydrates and 20% from protein; the subjects' goal was 10% weight loss over a six-month period and were given a daily multivitamin to take
  • Subjects then followed up with the RD every eight weeks to assess progress
  • The MR-FV Intervention Group attended weekly group sessions for 24 weeks: 90-minute "core" weight-loss classes for the first 12 weeks; 90-minute "ongoing" weight loss classes for the next four weeks; 60-minute "maintenance" classes for the last eight weeks
  • The MR-FV intervention was 1,200kcal per day and included a daily minimum of two meal replacement entrees and three prepared shakes, along with five servings of fruits and vegetables
  • Subjects were expected to attend class weekly, keep daily records of all MR and food intake, increase physical activity to 2,000kcal per week and make mid-week phone calls reporting nutrition intake and physical activity
  • During the maintenance phase, subjects consumed two MRs daily and continued to consume five servings of fruits and vegetables, maintain physical activity at 2,000kcal per week, maintain daily records and make mid-week phone calls reporting food intake and physical activity
  • Throughout the study period, subjects in the MR-FV Group were encouraged to consume at least the minimum recommended number of MRs and fruits and vegetables and avoid caloric foods not on their diet; MRs were provided weekly at no charge to subjects
  • Information was recorded weekly for the MR-FV Group by health educators in the behavioral-education classes and included class attendance, mid-week calls and subject weight. Subjects in this group also self-reported weekly the number of shakes, entrees, bars and servings of fruits and vegetables consumed; kcal of physical activity; days when only food on their diet prescription was consumed; days when the prescribed MR, fruits and vegetables were consumed; and days when goals for MR, fruit and vegetable consumption and physical activity were met.

Blinding Used

Only the two lead physicians were blinded to patient assignment.

Intervention 

The MR-FV intervention was:

  • 1,200kcal per day
  • Daily minimum of two meal replacement entrees and three prepared shakes
  • Five servings of fruits and vegetables
  • Weekly group behavioral-education classes
  • Physical activity at 2,000kcal per week
  • Daily records of intake and exercise
  • Mid-week phone calls reporting food intake and physical activity.

Statistical Analysis

  • Statistical procedures were done in as blinded a manner as possible and comparisons were made using two-sample independent T-tests
  • Intent-to-treat was also used.
Data Collection Summary:

Timing of Measurements

  • At the screening visit, after an overnight fast, baseline measures were taken for:
    • Complete blood count
    • Comprehensive metabolic panel
    • Lipid profile
    • Thyroid-stimulating hormone
    • Urinalysis
    • Weight
    • Waist circumference
    • Blood pressure
    • Height.
  • At Weeks Eight, 16 and 24, measurements were taken for:
    • Weight
    • Waist circumference
    • Blood pressure
    • Comprehensive metabolic panel
    • Lipid profile.

Dependent Variables

  • Percentage change in body weight
  • Change in risk factors (waist circumference, blood glucose and blood LDL-cholesterol).

Independent Variables

Group (MR-FV or UC) intervention and time.

Control Variables

None noted.

Description of Actual Data Sample:
  • Initial N: 45 subjects were randomized but only 38 enrolled (16 in the Control Group, 22 in the MR-FV Group; 29 were female)
  • Attrition (final N): 31 subjects completed (13 in the Control Group, 18 in the MR-FV Group)
  • Age: 45.4±10.2 years (Control Group), 50.5±7.3 (MR-FV Group)
  • Ethnicity: 15 subjects in the Control Group were Caucasian (93.8%), 20 subjects in MR-FV Group were Caucasian (90.9%). One subject in the Control Group was African-American (6.3%), two subjects in the MR-FV Group were African-American (9.1%)
  • Anthropometrics: Mean BMI of control subjects was 34.9± 2.7kg/m2 and mean BMI in the MR-FV Group was 35.8± 3.2kg/m2. Baseline values for risk factors were similar, except for mean fasting plasma glucose (5.2mmol per L in the MR-FV Group vs. 4.8mmol per L in the Control Group, P=0.026). 
  • Location: University of Kentucky, Lexington, KY.

 

Summary of Results:

Key Findings

  • During the weight-loss phase at Weeks Eight and 16, mean weight losses for the MR-FV Group were significantly greater than for the Control Group (8.7% and 14.3% vs. 1.7% and 1.5%, P<0.0001)
  • During the maintenance phase of Weeks 16 to 24, the MR-FV Group continued to lose weight and at 24 weeks, mean weight loss was 16.3% below baseline and was significantly different from the Control Group (-0.7% for ITT control subjects and -0.6% for control completers; P<0.0001 for both)
  • At 24 weeks, both groups decreased waist circumference but the difference was not significant (-5.3cm for the Control Group, -14.4cm for the MR-FV Group)
  • There was no significant difference between groups at 24 weeks for LDL-cholesterol (0.01mmol per L for the Control Group, -0.25mmol per L for the MR-FV Group)
  • At 24 weeks, there was a significant difference for glucose between groups (0.05mmol per L for the Control Group, -0.53mmol per L for the MR-FV Group, P<0.05).
Author Conclusion:
A behavioral intervention with a low-energy diet including five meal replacements and five servings of fruits or vegetables helped obese subjects lose 14.1% of their body weight (13.9kg) while control subjects lost only 0.7% (0.7kg) over a 24-week period.
Funding Source:
Reviewer Comments:
  • Not in a controlled environment for food consumption or exercise adherence
  • Subjects self-reported if they were following the prescribed diet or exercise plan.
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.) 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? Yes
  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.) Yes
  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? 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? 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? 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)? 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? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes