NC: Behavior Change Strategies (2007-2008)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
To investigate the contribution of meal and snack replacements for long-term weight maintenance and risk factor reduction in obese patients.
Inclusion Criteria:
Over 18 years of age, BMI between 25 - 40
Exclusion Criteria:
Individuals with a history of or presence of significant disease, endocrine disorders, psychiatric disorders, alcohol or drug abuse, or abnormal laboratory test results of clinical significance were excluded.  Women who were lactating, pregnant or wishing to become pregnant were also excluded. 
Description of Study Protocol:


Patients were referred by physicians because of past dissatisfaction with a standard energy-restricted diet plan for >3 months.


Prospective, randomized, two-arm parallel intervention for 12 weeks followed by a prospective single-arm 4-year trial.

Blinding used (if applicable)

Not blinded.

Intervention (if applicable)

Randomly assigned to 1 of 2 diets:  Group A received a 1200-1500 kcal control diet (19-20% kcals from protein, 48-54% kcals from carbohydrate, 25-34% kcals from fat), Group B received an isoenergetic diet, including 2 meal and snack replacements (Slim-Fast vitamin and mineral fortified shakes, soups and bars:  200-220 kcals, 14-17 g protein, 27-33.5 g carbohydrate, 5-6.6 g fat, 4.5-6.5 g fiber) and 1 meal high in fruits and vegetables (600 - 900 kcal, 30-45 g protein).  Following 3 months of weight loss, all patients prescribed the same energy-restricted diet (1200-1500 kcal) with 1 meal and 1 snack replacement for an additional 4 years.  Meal replacement products were provided for free.

Statistical Analysis

Weight loss over time was evaluated using generalized estimating equations.  Student's t test was used to make group comparisons of these measurements at each of the time points.  To adjust for multiple comparisons, a test was considered significant if its p value was less than 0.01.

Data Collection Summary:

Timing of Measurements

Patients received monthly instruction in behavior modification by the dietitian.  Phase I was a weight loss period of 3 months, followed by Phase II, a weight maintenance period of 4 years.  At scheduled intervals, blood pressure, anthropometric and lab measurements, and side effects recorded.  Blood samples and analyses were as reported.

Dependent Variables

  • Blood pressure, anthropometric and lab measurements:  methodology published elsewhere

Independent Variables

  • Dietary intervention:  Group A or Group B.  Food exchange lists and food diaries were used to equalize energy and protein intake between groups.

Control Variables


Description of Actual Data Sample:

Initial N: 100 subjects, 21 male, 79 female

Attrition (final N):  100 subjects after 12 weeks, 75 subjects after 4 years, 60 female, 15 male.  At the end of the second year, 63 completed the study.  By month 37, 58 patients continued.  32 of the 42 dropouts were located and 22 reentered the study between months 37 and 41.

Age:  Average age:  45.2 +/- 10.1 years 

Ethnicity:  Not mentioned. 

Other relevant demographics:  Patients encouraged to maintain usual level of activity.  Average BMI:  33.6 +/- 3.6  

Anthropometrics Initial demographics were not different between study groups.

Location:  University of Ulm Obesity Center, Germany 


Summary of Results:


Baseline (n=100) 3 months (n=100) 27 months (n=63) 51 months (n=75)
Body Wt - A 92.7 +/- 10.8 91.4 +/- 11.6 85.0 +/- 11.8 88.6 +/- 11.0
Body Wt - B 92.6 +/- 13.7 85.5 +/- 13.4 82.2 +/- 13.4 83.1 +/- 13.3
SBP - A 140 +/- 14 141 +/- 16 138 +/- 13 139 +/- 15
SBP - B 139 +/- 15 130 +/- 13 124 +/- 12 126 +/- 13
DBP - A 83 +/- 6 82 +/- 5 80 +/- 6 80 +/- 7
DBP - B 82 +/- 6 80 +/- 5 78 +/- 5 78 +/- 6
Triacylglycerol - A 2.13 +/- 1.34 2.15 +/- 1.50 1.77 +/- 0.62 1.44 +/- 0.42
Triacylglycerol - B 2.23 +/- 1.24 1.75 +/- 1.09 1.40 +/- 0.49 1.29 +/- 0.32
Cholesterol - A 6.01 +/- 0.94 5.84 +/- 1.00 5.69 +/- 0.60 5.58 +/- 0.52
Cholesterol - B 5.83 +/- 1.01 5.79 +/- 0.89 5.35 +/- 0.95 5.37 +/- 0.45
HDL-cholesterol - A 1.27 +/- 0.41 1.24 +/- 0.31 1.18 +/- 0.17 1.21 +/- 0.12
HDL-cholesterol - B 1.31 +/- 0.41 1.30 +/- 0.44 1.39 +/- 0.77 1.26 +/- 0.16
Blood glucose - A 5.05 +/- 0.85 5.07 +/- 0.79 4.52 +/- 0.42 4.40 +/- 0.34
Blood glucose - B 4.97 +/- 0.87 4.58 +/- 0.74 4.40 +/- 0.39 4.37 +/- 0.32
Insulin - A 134.6 +/- 50.4

139.1 +/- 63.2

98.8 +/- 30.0

92.6 +/- 17.1

Insulin - B 132.0 +/- 53.1

84.9 +/- 30.4

81.8 +/- 30.2

82.5 +/- 22.4

Other Findings

At 12 weeks, mean percentage weight loss was 1.5 +/- 0.4% for Group A and 7.8 +/- 0.5% for Group B. 

Systolic blood pressure, plasma triacylglycerol, glucose and insulin concentrations were significantly reduced in Group B, whereas no changes occurred in Group A.

After 4 years, total mean weight loss was significantly different:  3.2 +/- 0.8% for Group A and 8.4 +/- 0.8% for Group B (p = 0.001).

Both groups showed significant improvements in blood glucose and insulin (p < 0.01), but only Group B showed significant improvements in triacylglycerol and systolic blood pressure compared to baseline values (p < 0.01).

Author Conclusion:
There were 2 significant findings in this study.  First, patients reduced energy intake and maintained weight loss for 4 years.  Second, maintenance of weight loss promoted sustained improvements in several disease risk factors.  Providing a structured meal plan via vitamin- and mineral-fortified liquid meal replacements is a safe and effective dietary strategy for obese patients.  Long-term maintenance of weight loss with meal replacements can improve certain biomarkers of disease risk.
Funding Source:
Reviewer Comments:

0% dropout rate at 12 weeks, but dropout more significant over time.  Meal replacement products provided for free.  P significance set at 0.01.  Supported in part by Slim Fast Foods Co.

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) No
  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? 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%.) 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? No
  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? ???
  6.6. Were extra or unplanned treatments described? ???
  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? ???
  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? ???
  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? ???
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? ???