NC: Behavior Change Strategies (2007-2008)

Study Design:
- Click here for explanation of classification scheme.
Quality Rating:
Research Purpose:
  • The primary goal of the study was to test whether the delivery of reinforcement, contingent on the mastery of behavioral changes would improve the efficacy of behavioral treatment
  • A secondary goal was to evaluate the effectiveness of a minimal intervention, educational program for producing weight loss.
Inclusion Criteria:
Adults who were 20% to 100% over ideal body weight.
Exclusion Criteria:

Not given.

Description of Study Protocol:
  • Recruitment: Unspecified "advertisements" and physician referrals
  • Design: Randomized controlled trial; comparison of three different treatment groups.


  • Weight Loss Education (WLE) Group: Received a "minimal treatment" health-education program that provided information about appropriate methods for weight loss. This intervention involved six monthly lectures, supplemented by bibliography handouts on
    1. Proper nutrition and diet for weight loss
    2. Behavioral strategies for changing eating and exercise habits
    3. Guidelines for increasing physical activity.
  • Behavioral Therapy (BT) Group: Received 25 weekly treatment sessions that included training in self-monitoring, goal-setting, stimulus control and cognitive restructuring. Participants were asked to adhere to an average caloric intake of 1,200kcal (women) or 1,500kcal (men) and to limit fat intake to 30% of total kcal per day and to work toward a goal of 30 minutes of walking, six days per week. Participants were rewarded with $1 per week for attending treatment session and $1 per week for presentation of complete eating and exercise records.
  • Behavior Therapy + Personalized Skill Acquisition (BT+PSA) Group: Received the same weekly training as did the BT group. Ultimate goals for caloric consumption, fat intake and exercise were the same as for the BT group, but individuals worked toward them in increments defined by mastery criteria. Weekly goals and contingency contracts (mastery criteria) were established; training and reinforcement were paced according to individual mastery of specified self-management skills within nine levels that successively approximated desired goals for diet, activity and knowledge. Reinforcement was given when all the mastery criteria within a certain level were met.

Statistical Analysis

Repeated-measures analysis of variance procedures used to analyze differences between conditions in changes in the dependent variables over time. Significant effects were evaluated further with Newman-Keuls tests.

Data Collection Summary:

Timing of Measurements

  • Body weights were measured at zero, three and six months
  • All other dependent measures were taken at zero and six months.

Dependent Variables

  • Variable One: Body weight (specifics of how measurement was taken not given)
  • Variable Two: Total caloric intake and intake from fats, derived from three-day food records, analyzed using the Minnesota Nutrient Data System (Nutrition Coordinating Center, 1990)
  • Variable Three: Daily average minutes of exercise, calculated from seven-day self monitoring records (collected from participants in the BT and BT+PSA groups only)
  • Variable Four: Knowledge of nutrition, physical activity and behavioral strategies for weight loss as measured by a face valid questionnaire.  

Independent Variables

Independent Variable One: Percentage overweight at baseline.

Control Variables

Age, education and body weight differences between groups.

Description of Actual Data Sample:
  • Initial N: 108 participants; 80 women and 28 men
  • Attrition (final N): 86 participants (20.4% drop-out rate)
  • Age: Not given
  • Ethnicity: Not given
  • Other relevant demographics: None given.


  • Body weight (20 to 100% over weight)
  • Group mean weights
    • WLE: 98kg (SD 15.3)
    • BT: 97.2kg (SD 15.8)
    • BT+PSA: 93.7 (SD 15.5).


  • Presumably University of Florida, Gainesville, Florida, where authors are from
  • Setting or location of study not given within body of paper.
Summary of Results:


Treatment Group I WLE N=17
(Measures and confidence intervals)

Treatment Group II BT N=36
(Measures and confidence intervals)

Treatment Group III BT + PSA N=33
(Measures and confidence intervals)

Statistical Significance of Group Difference

Dependant Variable One: Body weight change from zero to three and zero to six months

-0.8 (CI not given)

-6.5kg (CI not given)

-5.7kg (CI not given)

Within group differences significance for BT and BT+PSA P<0.05

Between-group differences BT and BT+PSA significant different from WLE  P<0.05

BT and BT+PSA not significantly different

Dependant Variable Two: Kcal intake, kcal from fats from zero to six months




Total kcal and fat kcal: Within group differences significant for BT and BT+PSA P<0.05

Within group difference for WLE N to significance 

Total kcal and fat kcal: Between group differences BT and BT+PSA significant different from WLE

BT not significant from BT+PSA

Dependant Variable Three: Exercise (daily average minutes)


+65.3 minutes


Within group difference significance P<0.05

Between group difference not significant

Dependant Variable Four: Knowledge (units)

+1.9 +2.3 +1.9

Within group differences significant for all three groups P<0.05

Between group differences not significant

Other Findings

  • A significant difference was observed in monetary reinforcement received by participants within the two behavioral treatment conditions (P<0.05)
  • Participants in the BT group received a greater percentage (M=82.2%) of the total number of dollars possible than did individuals in the BT+PSA group (M=70.4%)
  • This difference was related to the fact that within the BT+PSA group the mean Mastery Level completed at the end of treatment was seven (of nine possible)
  • The BT group received reinforcement for showing up for meetings and completing records, whether or not mastery of a skill was demonstrated
  • The BT+ PSA group only received reinforcement when mastery of a skill level was demonstrated, whether or not records were completed.
Author Conclusion:
  • Both behavioral treatments demonstrated significant beneficial changes in caloric consumption, intake of fats and level of physical activity and both resulted in significant weight loss
  • The combination of Behavioral Treatment and Personalized Skill Acquisition was no more effective than the Behavioral Treatment alone
  • Both Behavior Treatment programs produced significantly greater results than the Weight-Loss Educational program, which was much less expensive. However, recent changes in health care delivery systems in the US highlight the need for the further development of time-efficient and cost-effective approaches to obesity treatment.
Funding Source:
Reviewer Comments:
  • This study definitely showed benefits from behavioral treatment for weight management and lack of significant benefit from weight loss education alone over six months
  • The lack of information regarding participant ages, health status, and demographics, setting of study and reasons for attrition decreased the quality rating of this study.
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? No
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? No
  2.2. Were criteria applied equally to all study groups? No
  2.3. Were health, demographics, and other characteristics of subjects described? No
  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? ???
  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? No
  4.1. Were follow-up methods described and the same for all groups? No
  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? No
  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? 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? 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? 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? No
  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)? Yes
  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? No
  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? ???
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
10. Is bias due to study's funding or sponsorship unlikely? Yes
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? Yes