DM: Weight Management (2001)

Citation:
 
Study Design:
Class:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:

To identify a large sample of individuals who were successful at long-term maintenance of substantial weight loss and to use quantitative measures to describe their weight loss and weight maintenance strategies.

Inclusion Criteria:

Based on the criteria for registering with the National Weight Control Registry:

1. Must have lost >=13.6 kg (30 lb)

2. Maintained the weight loss for >=1 yr.

3. >=18 yr of age

Exclusion Criteria:
Anyone not meeting the above described standards.
Description of Study Protocol:

Recruitment: Subjects were recruited by local and national media sources, mailings to commercial weight loss programs, and articles in newsletters and magazines.

Design: Subjects were asked a series of questions about demographic and weight characteristics, weight loss methods and strategies, and weight maintenance methods and strategies, and the effect of weight loss and maintenance on selected aspects of their lives. The measures used to assess these variables include:

  • Demographic and weight characteristics
  • Weight loss methods
  • Weight maintenance methods
  • Previous weight loss attempts
  • Difficulty of weight loss and weight maintenance
  • Effect of weight loss on other areas of life

Blinding Used: N/A

Intervention: N/A

Statistical Analysis: Data was expressed as means + SDs. Between group comparisions (men compared to women) were made with the use of unpaired t tests or chi-squared tests.

Data Collection Summary:

Timing of Measurements:

Subjects completed comprehensive packet of questionnaires.

Dependent Variables:

  • Weight loss and weight maintenance strategies assessed through Block food frequency questionnaire, Paffenbarger physical activity questionnaire, other questionnaires

Independent Variables:

  • Demographic and weight characteristics

Control Variables:N/A

Description of Actual Data Sample:

Initial N:784 subjects, 629 women, 155 men

Attrition (Final N): no change reported

Age: mean age: 45.29 + 11.77

Ethnicity: 96.9% Caucasian, 1.4 % African American, 0.1% Asian, 1.1% Hispanic, 0.4% Other.

Other Relevant Demographics:

  • Education (%): High school or less: 18.4, Some college: 27.8, College or University degree: 25.4, Graduate degree: 28.4.
  • Marital status (%): married: 67.3, Separated or divorced: 11.1, Single: 21.6 
  • Weight loss method (%): On own: 44.6, Formal program: 55.4
  • Duration of weight loss (yrs): 5.57 + 6.82

Anthropometrics:

  • Change in weight (kg): 30.00 + 15.49
  • Change in BMI: 10.57 + 5.23
  • Maximum weight (kg): 99.85 + 24.25
  • Maximum BMI (kg/m2): 35.12 + 7.27
  • Current weight (kg): 69.85 + 14.47
  • Current BMI (kg/m2): 24.56 + 4.03

Location: US

 

Summary of Results:

Parameter Men Women P Value
Formal Program for Weight Loss (%) 37.0 60.0 P<0.001
Limited Quantity of Food (%) 32.0 47.2 P<0.0008
Expenditure of energy via heavy-intensity activities ( kJ/wk) 5285 + 7751 2888 + 5893 P< 0.001
Weight loss was easy ( %) 36.8 23.9 P= 0.004
 

Other Findings:

  • The subjects had maintained a 30 lb weight loss for an average of 5 years.
  • Mean intakes were ~1380 kcal and mean expenditure was ~2830 kcal/d
  • The triggering event for weight loss was medical for 32.4%, emotional for 31.7%, and lifestyle for 26.2%.
  • At least 85% of the sample reported improvements in energy, physical mobility, general mood, self-confidence, and physical health as a result of weight loss.
  •  No sex differences in the proportions of subjects rating weight maintenance more, less, or as difficult as weight loss.
Author Conclusion:

This registry identified a large sample of individuals who were highly successful at maintaining weight loss. Future prospective studies will determine variables that predict continued maintenance of weight loss.

Funding Source:
University/Hospital: University of Philadelphia, University of Colorado
Reviewer Comments:
This retrospective study demonstrates the need to make permanent lifestyle changes by decreasing kcal intake to ~1400 kcal/day while at the same time increasing physical activity to ~2800 kcal/day for weight loss and maintenance.
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) N/A
 
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? N/A
  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? N/A
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) N/A
  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? 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? 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? 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? N/A
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? N/A
  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? N/A
  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)? 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? Yes
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? Yes