Adult Weight Management

NC: Behavior Change Strategies (2007-2008)

Citation:

Ditschuneit HH, Flechter-Mors M, Johnson TD, Adler G.  Metabolic and weight-loss effects of a long-term dietary intervention in obese patients.  Am J Clin Nutr 1999; 69(2): 198-204.

PubMed ID: 9989680
 
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:
To test the hypothesis that meal replacements are a useful tool for sustained weight loss and that minimal, sustained weight loss will maintain improvements in biomarkers of disease risk.
Inclusion Criteria:
Patients were men and women aged > 18 years whose BMI were between 25 - 40 and who gave their informed consent to participate.  Patients indicated their willingness to be randomly assigned to study groups and to follow the program protocol.
Exclusion Criteria:
Individuals with a history or presence of significant disease, endocrine disorders, psychiatric diseases, alcohol or drug abuse, or abnormal laboratory test results of clinical significance were excluded.  In addition, women were excluded if they were lactating, pregnant, or wishing to become pregnant.
Description of Study Protocol:

Recruitment

Study patients were referred to the Obesity Center at the University Hospital of Ulm for obesity management.  All patients had been treated by the referring practitioner with energy-restricted diets for > 3 months and were dissatisfied with the degree of weight loss.

Design

Randomized Controlled Trial.

Blinding used (if applicable)

Not blinded.

Intervention (if applicable)

The study was 27 months in duration and consisted of 2 phases.  Phase 1 consisted of a 3-month prospective, randomized, parallel intervention study of 2 dietary interventions to reduce weight.  Subjects were randomized by a computer-generated identification number.  The energy-restricted diet (5.2 - 6.3 MJ/day, 1200-1500 kcals/day, 19-21% kcals from protein, 48-54% kcals from carbohydrate, 25-34% kcals from fat) consisted of conventional foods (group A) or an isoenergetic diet with 2 meals and 2 snacks replaced daily by energy-controlled, vitamin & mineral supplemented prepared shakes, soups or hot chocolate (group B).  Meal replacement foods contained 0.84 - 1.05 MJ energy 14-17 g protein, 27-33.5 g carbohydrate, 5-6.6 g fat and 4.5-6.5 g fiber.  Phase 2 consisted of a 24-month, case-control weight maintenance study with an energy-restricted diet and 1 meal and 1 snack replaced daily for all patients.  Patients were encouraged to maintain their usual level of physical activity throughout both phases of study. 

Statistical Analysis

Comparisons of baseline values between the 2 groups, within a sex, were calculated by using a two-sample t test.  Values are given as means +/- SDs, unless stated otherwise.  For phase 1, a linear regression model was fit for percentage weight change and absolute body weight with sex and group as covariates.  The sex-by-group interaction was also considered.  Treatment group was the only significant predictor of percentage weight change and absolute body weight.  For all secondary outcome variables, a two-sample t test was used to compare the 2 groups.  A paired t test was also used to test whether there were significant changes from baseline to 3 months for each group within a sex.  Generalized estimating equations were used to analyze phase 2 of the study.  An unstructured, working correlation matrix was assumed for the GEE algorithm for all outcomes except percentage weight change, for which a compound, symmetric structure was assumed.  For each outcome of interest, a GEE model was fit with sex, group, time, and baseline outcome as main effects and all interactions between sex, group and time.  All outcomes were measured at 3, 15 and 27 months with the exception of anthropometric characteristics, which were measured monthly.

Data Collection Summary:

Timing of Measurements

Monthly hospital visits for physical exams and review of diet records.  Measurements made at each visit under similar conditions.  Blood samples taken at baseline, 3 months, and every 12 months thereafter.

Dependent Variables

  • Body weight measurements taken to nearest 0.1 kg using the same precision scale with patients dressed only in underwear
  • Waist and hip circumferences measured to nearest 0.5 cm using nonstretchable tape measure.  Waist circumference was measured midway between the lower rib margin and the iliac crest.  Hip circumference was measured at the widest point of the trochanter and buttocks area.
  • Blood pressure was measured on upper right arm by using a mercury column manometer to the nearest 5 mm Hg at 08:00 with the patient in a supine position and after the patient had rested for > 10 minutes.
  • Blood samples taken at 08:00, > 10 hours after previous meal.  Biochemical measurements performed using standard methods.

Independent Variables

  • Dietary intervention:  staff nutritionist explained diet plan in detail and counseled participants by using personalized sample menus and recipes and instruction in maintenance of a food diary.  Nutritionist provided monthly personalized instructions by using food exchange lists and food diaries to equalize prescribed energy intakes between groups.  Accurate daily recording was stressed and daily food diaries were maintained for 7 consecutive days during the 2-week period before each visit.  Records were reviewed with each patient and analyzed monthly by the nutritionist.  Nutrient calculations carried out using German Food Code BLS and the NutriLog program.

Control Variables

 

Description of Actual Data Sample:

Initial N: 100 obese subjects

Attrition (final N):  100 subjects completed phase 1, 63 completed phase 2.  37 dropouts were 19 in group A and 18 in group B.  Withdrawals were due to clinical events, social or domestic events, unwillingness to comply with the protocol, or unknown reasons.

Age:  Group A women (n=41):  46.8 +/- 11.2 years, men (n=9):  45.5 +/- 12.0 years.  Group B women (n=38):  44.3 +/- 9.8 years, men (n=12):  46.5 +/- 9.5 years. 

Ethnicity:  Not mentioned. 

Other relevant demographics:

Anthropometrics There were no significant differences between the 2 groups in sex distribution, age, body weight or BMI.

Location: University of Ulm, Germany

 

Summary of Results:

 

Phase 1 - Baseline (n=100) Phase 1 - 3 months (n=100) Phase 2 - 15 months (n=78)

Phase 2 - 27 months (n=63)

Body weight - A 92.7 +/- 10.8 91.4 +/- 11.6 87.5 +/- 12.1 85.0 +/- 11.8
Body weight - B 92.6 +/- 13.7 85.5 +/- 13.4 84.3 +/- 13.8 82.2 +/- 13.4
Waist to hip ratio - A 0.90 +/- 0.10 0.86 +/- 0.21 0.85 +/- 0.24 0.84 +/- 0.18
Waist to hip ratio - B 0.89 +/- 0.12 0.86 +/- 0.18 0.85 +/- 0.20 0.85 +/- 0.19
SBP - A 140 +/- 14 141 +/- 16 135 +/- 12 138 +/- 13
SBP - B 139 +/- 15 130 +/- 13 123 +/- 11 124 +/- 12
DBP - A 83 +/- 6 82 +/- 5 78 +/- 5 80 +/- 6
DBP - B 82 +/- 6 80 +/- 5 76 +/- 5 78 +/- 5
Triacylglycerol - A 2.13 +/- 1.34 2.15 +/- 1.50 1.65 +/- 0.53 1.77 +/- 0.62
Triacylglycerol - B 2.23 +/- 1.24 1.75 +/- 1.09 1.58 +/- 0.41 1.40 +/- 0.49
Cholesterol - A 6.01 +/- 0.94 5.84 +/- 1.00 5.45 +/- 0.93 5.69 +/- 0.60
Cholesterol - B 5.83 +/- 1.01 5.79 +/- 0.89 5.51 +/- 0.53 5.35 +/- 0.95
HDL cholesterol - A 1.27 +/- 0.33 1.24 +/- 0.31 1.24 +/- 0.26 1.18 +/- 0.17
HDL cholesterol - B 1.31 +/- 0.41 1.30 +/- 0.44 1.24 +/- 0.30 1.39 +/- 0.77
Blood glucose - A 5.05 +/- 0.85 5.07 +/- 0.79 4.55 +/- 0.40 4.52 +/- 0.42
Blood glucose - B 4.97 +/- 0.87 4.58 +/- 0.74 4.75 +/- 0.63 4.40 +/- 0.39
Insulin - A 134.6 +/- 50.4

139.1 +/- 63.2

93.1 +/- 28.4

98.8 +/- 30.0

Insulin - B 132.0 +/- 53.1

84.9 +/- 30.4

96.2 +/- 48.0

81.8 +/- 30.2

Other Findings

Total weight loss (as a percentage of initial body weight) was 5.9 +/- 5.0% in group A and 11.3 +/- 6.8% in group B (P < 0.0001). 

During phase 1, mean weight loss in group B (n=50) was 7.1 +/- 3.5 kg, with significant reductions in plasma triacylglycerol, glucose, and insulin concentrations (P < 0.0001).  Group A patients (n=50) lost an average of 1.3 +/- 2.2 kg with no significant improvements in these biomarkers.

During phase 2, both groups lost on average an additional 0.07% of their initial body weight every month (P < 0.01). 

During the 27-month study, both groups experienced significant reductions in systolic blood pressure and plasma concentrations of triacylglycerol, glucose and insulin (P < 0.01). 

Author Conclusion:
In conclusion, long-term dietary interventions in obese patients that include the use of nutrient-dense meal replacement products were effective in improving long-term weight control in addition to blood pressure and metabolic biomarkers of comorbid disease. 
Funding Source:
Industry:
Slim Fast Food Company
Food Company:
Reviewer Comments:
Physical activity not monitored.  Large number of dropouts during phase 2.  Funded by Slim Fast.
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? 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? No
  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? ???
  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? 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)? No
  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? ???