Development and Testing of an Enhanced Homework Procedure for a Weight Loss Management Group Intervention

Identifying what factors can increase participants adherence to a weight management program is of great interest. The usage of between session activities in psychotherapy have also been determined to increase overall client outcomes. By adding evidence-based homework principles to a weight management program, it is believed that the completion of between session activities will improve. It is expected that between session activities will increase client self-efficacy, dietary and exercise behaviors, and overall weight loss. The purpose of this study was to investigate whether the addition of a systematic and structured homework procedure would translate to increased weight loss outcomes. At a local HMO, a total of 56 participants were randomly assigned to either the standard weight loss group (treatment as usual) or the enhanced group (treatment as usual plus addition of homework principles). Participants completed a 16-week weight management program and the current study assessed the effect of the enhanced component on self-efficacy, dietary and exercise behaviors, and overall weight loss. Overall attrition rate for the study was 17.9% and session attendance rate by participants was 70% (enhanced group) and 63% (standard group). The mean score of completed food logs was higher for the enhanced group (6.85) compared with the standard group (6.08), however the difference was not statistically significant, t (50)=0.63, p=0.53. The same pattern was also observed for the Between Session Activities Questionnaire (BSAQ) scores, t (50)=.23, p=0.82. In a series of ANCOVA analyses with pretreatment scores as covariates, the Weight Efficacy Life-style Questionnaire (WEL) post assessment scores did not significantly differ between the enhanced and standard group, F (1,42)=3.29, p=0.08; partial ç2= .073; likewise the Exercise Self-Efficacy Scale (ESES) post assessment scores did not significantly differ between the two groups, F (1,42)=0.22, p=0.64; partial ç2= .005. The Dietary Habits Questionnaire (DHQ) post assessment scores also did not significantly differ between the two groups, F (1,42)=1.24, p=0.27; partial ç2= .028, and neither were post assessment scores on the Paffenbarger Physical Activity Questionnaire (PPAQ) F (1,42)= .18, p=.67; partial ç2= .004. Lastly, there was no significant difference in weight loss between the enhanced and standard group, F (1,53)= 3.68, p=0.06, partial ç2=.065. However, an interaction effect was detected between Time x Group for weight loss, F (1,53)= 4.04, p= .049, partial ç2= .070, favoring the enhanced treatment group, in a supplementary repeated measures ANOVA analysis. This was further supported by the results of the multi-dimensional chi square test, which indicated that there was a marginal relationship between the condition (enhanced vs. standard) and the 7% weight loss goal achievement: ×2 (1, N=56) = 3.82, p=0.051(three times more respondents in the enhanced condition achieved the 7% goal than in the standard condition). In terms of the 5% weight loss goal, the number of respondents who achieved this goal is relatively the same for both conditions (×2 (1, N=56) = 3.11, p=0.557). Additional repeated measures ANOVA analyses suggested that both groups improved on the WEL and DHQ, however differences between the groups were not detected. This indicates that the enhanced homework procedure was unable to produce greater levels of weight management self-efficacy and the adoption of healthy eating behaviors beyond what would be expected of the standard treatment. Furthermore, neither the standard or enhanced groups improved on levels of exercise self-efficacy and the adoption of exercise behaviors. The current study was unable to detect clear differences between the enhanced and standard homework conditions on all measures (partly likely due to the limited sample size). However, there were moderate effect sizes observed favoring the enhanced condition on some measures, such as the WEL, and most importantly, the overall weight loss. It is possible that since both conditions included some homework elements, and the time allocated to differentiating and enhancing the homework effects in the enhanced condition was somewhat limited, there was not sufficient potency in the enhanced condition to produce clearly visible statistically significant differences on all measures between groups in a relatively modest sample size. Determining ways to increase the completion of between session activities by weight loss group participants is considered a step in the right direction in achieving weight loss, and fighting obesity.