The effects of if-then plans on weight loss: results of the 24-month follow-up of the McGill CHIP Healthy Weight Program randomized controlled trial

BACKGROUND: Current evidence suggests that some of the most effective weight loss approaches are changes in dietary and physical activity behaviors through lifestyle modification programs. The Group Lifestyle Balance (GLB) program is a group-based behavior modification program aimed at changing diet and physical activity for weight loss. It was developed to be more cost-effective and easier to disseminate than its individually administered parent program, the Diabetes Prevention Program (DPP). However, the average weight loss following participation in the GLB is only approximately 3.5%, with low long-term weight loss maintenance. PURPOSE: We aimed to optimize the weight loss outcomes of the GLB to increase the efficacy already afforded by its cost-effectiveness and ease of dissemination. We did this by integrating the habit formation tool of if-then plans into the program. This program is called the enriched GLB or the McGill Comprehensive Health Improvement (CHIP) Healthy Weight Program. Results at 3 and 12 months of participation have already been published elsewhere. They showed no between-group differences between the standard and enriched GLB but higher weight loss in both groups compared to the DPP. This paper reports the long-term weight loss maintenance data following participation in the program. METHODS: Of the 172 participants enrolled at the beginning of the study, data from 110 participants were available and analyzed at 24 months, i.e., 12 months after the end of the 12-month intervention. RESULTS: No between-group difference in weight loss maintenance was observed. Pooled results showed a significant weight regain from 12 to 24 months, i.e., an average of 7.85 lbs. of the 20.36 lbs. lost. However, participants from both groups were still 12.51lbs or 6.13% lighter at 24 months than at baseline. CONCLUSION: If-then plans did not result in a higher percentage of weight loss at 24-month follow-up compared to the standard GLB. However, at 24 months, both groups did show a maintenance of a significant portion of the weight lost at the end of intervention. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02008435, registered 6 December 2013.