Adult Weight Management

AWM: Meal Replacements (2006)

Citation:

Rothacker DQ.  Five-year self-management of weight using meal replacements:  comparison with matched controls in rural Wisconsin.  Nutrition 2000; 16(5): 344-348.

PubMed ID: 10793302
 
Study Design:
Non-Randomized Controlled Trial
Class:
C - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:
To compare 5-year weight changes of subjects after a self-managed meal-replacement weight-control program with that of matched control subjects in rural Wisconsin.
Inclusion Criteria:
Overweight but otherwise healthy adults, aged 18 - 65 in 1992.
Exclusion Criteria:
Subjects experiencing a weight-affecting condition between 1992 and 1997, such as pregnancy, cancer, death, thyroid conditions requiring medication, and serious gastrointestinal disease.
Description of Study Protocol:

Recruitment

Subjects recruited from 2 rural neighboring villages in northern Wisconsin for participation in an open-label program of weight loss and weight maintenance.

Design

Nonrandomized Clinical Trial.

Blinding used (if applicable)

Not applicable.

Intervention (if applicable)

Subjects were instructed to follow the label instructions of a popular 200-220 kcal fortified, meal-based meal replacement diet shake product that replaced 2 meals per day during the first 3 months and 1-2 meals per day until ideal weight was achieved.  For maintenance, they either replaced 1 meal per day with a shake or monitored weight daily - if they gained more than 1-2 kg, they were instructed to return to regular use of the meal replacements.  No medical intervention (clinic visits, behavior modification, exercise program) was provided.  Meal replacement products provided for free.

Statistical Analysis

Data for age and BMI are presented as mean +/- SD.  Paired t tests were performed to determine whether a significant change in BMI and weight had occurred.  All statistical tests were two-tailed and were performed with SPSS.  Dropouts in the program participant dataset were not analyzed statistically because only 5 who could have been in meal-replacement dataset left the program.

Data Collection Summary:

Timing of Measurements

Subjects asked to weigh in weekly for the first 3 months and then weighed twice a year from 1992 - 1997.  Recorded weights from 3 area clinics obtained in 1992 and 1997 for 528 healthy males and females, and 378 self-reported weights from 1992 and 1997 for area males and females obtained by questionnaire.

Dependent Variables

  • 1997 body weights obtained with balance-beam scale at local village center

Independent Variables

  • Dietary intervention of meal replacement shakes.  Compliance not monitored.

Control Variables

 

Description of Actual Data Sample:

Initial N: 158 subjects, 108 females, 50 males, 3 matched controls selected per subject. 

Attrition (final N):  After 5 years, 141 participants weighed in.  906 area control subjects.  Of missing 17 females, 6 lost to follow-up or did not wish to continue, 2 died of cancer, 19 excluded from analysis, primarily due to pregnancy.  No subject was dropped from the study for any reason, including noncompliance.  Only 6 females lost to follow-up after 5 years.  22 controls excluded for weight affecting conditions after review of medical history.

Age:  1992:  Meal replacement females:  mean age 41.4 +/- 10.6 years, matched female controls:  mean age 42.0 +/- 10.5 years, meal replacement males:  mean age 40.3 +/- 10.3 years, matched male controls:  mean age 40.3 +/- 10.0 years. 

Ethnicity:  Caucasian and of similar ancestral background 

Other relevant demographics:  Population fairly homogeneous 

Anthropometrics:  Controls matched for age within 5 years, BMI within 2 kg/m2, race, gender, health status and residency within a 50-mile radius of the program center.

Location: Wisconsin

 

Summary of Results:

Other Findings

The 50 males were -5.8 +/- 5.4 kg and the 84 females were -4.2 +/- 6.9 kg from their 1992 weights (P < 0.001 compared with baseline).  More than 80% of the females and 90% of the males weighed less or were within 0.8 kg of their 1992 weight.

Conversely, 142 matched male controls gained 6.7 +/- 10.2 kg and 247 female controls gained 6.5 +/- 10.7 kg (P < 0.001 compared with baseline).  Only 27% of females and 22% of males had not gained weight (>0.8 kg).

Author Conclusion:
In conclusion, a self-managed weight-control program using meal-replacement diet shakes has been shown to be successful in weight controll and in the prevention of weight regain over a 5-year period in a rural adult population that is overweight to obese.  Long-term programs of weight control should take into account the background rate of weight gain because they become an increasingly important factor with time.  Being obese or overweight and at baseline weight 5 years later is not necessarily a failure as it is usually considered.  In this study, the amount of weight gained by the controls was greater over the 5-year period than the amount of weight kept off by the participants, making not gaining a success in itself. 
Funding Source:
Reviewer Comments:
Dietary compliance not monitored.  Some 1992 control weights were self-reported, but there were 3 controls per subject.  All subjects were Caucasian and from rural Wisconsin - limited generalizability.  Supported by Slim Fast Foods.
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? No
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? N/A
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? N/A
  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.) N/A
  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? 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? No
  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? No
  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)? ???
  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? ???