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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; 16:344-348

PubMed ID: 11950336
 
Study Design:
Prospective Cohort Study
Class:
B - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

The five year progress of subjects using a self-managed weight-control program using meal replacements was compared with that of control subjects. The controls were matched for age, BMI race, gender, health status, and residency within a 50-mile radius of the program center since 1992. 

Inclusion Criteria:
  • Overweight
  • Age 18-65 years (in 1992)
  • Healthy.
Exclusion Criteria:
  • Unhealthy adults
  • Not overweight 
  • Presence of a weight-affecting condition, such as pregnancy excluded some potential participants as well as caused several to drop out of the study.
Description of Study Protocol:


 

Recruitment:

Subjects were recruited from two rural neighboring villages in northern Wisconsin

Intervention:

  • Months zero to three: Subjects were instructed to follow the label instructions of a popular 200-220 calorie, fortified, milk-based meal replacement diet shake product that replaced two meals each day
  • After three months: Meal replacement product used in place of one to two meals each day until their ideal weight was achieved
  • For maintenance, they either replaced one meal each day with a shake or monitored their weight daily
  • If they regained more then 1-2kg, they were instructed to return to regular use of the meal replacements
  • No other interventions or changes were made 
  • The subjects were followed for five years
  • Controls were matched to each subject, 3 to 1 for gender, 1992 BMI within 2kg/m2, and age within five years.

Statistical Analysis

  • Significance of change in BMI and weight: Paired T-tests (two-tailed)
  • Dropouts not analyzed; N too small.

 

Data Collection Summary:

Timing of Measurements

  • Subjects weighed in every week for the first three months at the village center, and weight was recorded on case-report forms
  • After the initial weight loss phase, subjects were only seen twice a year 
  • Control data (225 males and 303 females) was obtained from review of case records from three major medical centers within 50 miles of the study center to determine if:
    • Inclusion/exclusion criteria were met
    • An official record of weight in 1992 was in the record 
    • Other controls (115 males and 263 females) self-reported weight from 1992. 

Dependent Variables

Weight and BMI change: Weight measured using scale

Independent Variables

Meal replacement use

Description of Actual Data Sample:
  • Initial N:  
    • Meal replacement group: Males: N=50; Females: N=91
    • Matched Controls: Males: N=142; Females: N=247
  • Final N:
    • Meal replacement group: Males: N=50; Females: N=84
    • Matched Controls: Males: N=142; Females: N=247

 Age, Weight and BMI of Meal Replacement Participants and Matched Controls in 1992

Variable Mean SD Range
Meal Replacement Participants   

Females (N=84)

Age (years)

Weight (kg)

BMI

 

41.4

81.2

30.7

 

10.6

14.7

5.6

 

19-64

54-125

21-51

Males (N=50)

Age (years)

Weight (kg)

BMI

 

40.3

102.9

32.5

 

10.3

15.3

4.4

 

20-64

77-141

26-47

Matched Controls   

Females (N=247)

Age (years)

Weight (kg)

BMI

 

42.0

80.6

30.2

 

10.5

15.8

  5.6

 

20-69

46-125

20-49

Males (N=142)

Age (years)

Weight (kg)

BMI

 

40.3

96.3

31.7

 

10.0

15.2

  4.9

 

21-61

60-147

24-46

  • Other Demographics: Sample was homogenous with respect to income, ethnic diversity, religion, and education
  • Location: Two rural villages in northern Wisconsin.

 

Summary of Results:

Initial weight loss of Meal Replacement participants:

  • Females: 6.4±0.9kg
  • Males: 7.4±1.7kg
  • Regain of weight was significant (P-value not given).

Age, Weight,BMI, Weight Change, and BMI Change of Meal-Replacement
Participants and Matched Controls in 1997

Variable Mean S.D. Range Significance
Meal Replacement    

Females (N=84)

BMI

BMI Change

Weight (kg)

Weight change (kg)

No. (percent) not gaining 0.8kg: 69 (82.1%)

 

29.1

-1.6

77.1

-4.2

 

6.0

2.6

15.8

6.9

21 to 51

-10 to +10

42 to 130

-27 to +22

P≤0.001

Males (N=50)

BMI

BMI Change

Weight (kg)

Weight Change (kg)

No. (percent) not gaining 0.8kg:46 (92.0%)

30.6

-1.8

97.1

-5.8

 4.6

1.8

16.2

5.4

23 to 43

-5 to +4

68 to 134

-18 to +13

 P≤0.001
Matched Controls    

Females (N=247)

BMI

BMI Change

Weight (kg)

Weight Change (kg)

No. (percent) not gaining 0.8kg: 66 (26.7%)

32.7

2.5

86.1

+6.5

 6.2

4.1

16.7

10.7

21 to 49

-15 to +16

55 to 129

-38 to +41

 P≤0.001

Males (N=142)

BMI

BMI Change

Weight (kg)

Weight Change (kg)

No. (percent) not gaining 0.8kg: 31 (21.8%)

33.9

2.2

103.1

+6.7

 5.9

3.5

18.0

10.2

 23 to 53

-8 to +15

61 to 170

-25 to +35

 P≤0.001

 

Author Conclusion:

A self-managed weight control program using meal-replacement diet shakes has been shown to be successful in weight control and in the prevention of weight gain over a five-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 changes for that population because they become an increasingly important factor with time. Being obese or overweight and at baseline weight five 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 five-year period than the amount of weight kept off by the participants, making not gaining a success in itself.

Funding Source:
Industry:
Slim Fast
Food Company:
Reviewer Comments:

This study is interesting because it considers long-term results of weight loss attempts. However there are so many unknown factors that may be important to consider in the results.Those who tried the weight loss program were obviously interested in losing weight and were perhaps taking other measures to lose weight such as exercise or other diet changes. The controls may have not had any interest in losing weight and therefore to compare these two groups is difficult.This study cannot prove that meal-replacement shakes are the most effective weight loss method. It simply shows that some weight loss or weight management can prevent gains later in life. The research was funded entirely by Slim-Fast.  Claims made by the study are not necessarily supported.

By comparing the participants to three control subjects findings are stronger than if just one control was used. Also 35% of females self-reported their 1992 weight, which is not reliable.

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? ???
  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) N/A
  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? Yes
  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? N/A
  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? N/A
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  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? N/A
  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? No
  7.7. Were the measurements conducted consistently across groups? No
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)? N/A
  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? ???