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United States Department of Agriculture

Agricultural Research Service

Research Project: Dietary Guidelines Adherence and Healthy Body Weight Maintenance Title: Do weight loss and adherence cluster within behavioral treatment groups?

Author
item Raatz, Susan

Submitted to: Obesity
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 28, 2013
Publication Date: March 3, 2014
Citation: Raatz, S.K. 2014. Do weight loss and adherence cluster within behavioral treatment groups? Obesity. 22(3):638-644.

Interpretive Summary: Weight loss programs are often conducted in a group format, but it is unclear if characteristics of the treatment group affect outcomes. We examined these questions within Look AHEAD, a multicenter study of the effects of an intensive lifestyle intervention (ILI) in overweight/obese individuals with type 2 diabetes. Weight losses and adherence to treatment were examined over one year of intervention in ILI participants in 209 different treatment groups. Weight losses did not cluster among members of a treatment group, whereas measures of adherence had small/moderate clustering and neither size nor baseline homogeneity of group members affected the outcome. Although these findings suggest that it may not be necessary to control for clustering in behavioral weight loss studies, they also indicate that merely treating individuals in groups is not sufficient to harness social influences on weight loss.

Technical Abstract: Objective: Weight loss programs are often conducted in a group format, but it is unclear whether weight losses or adherence cluster within treatment group and whether characteristics of the group (e.g., size or homogeneity) affect outcomes. We examined these questions within Look AHEAD, a multicenter study of the effects of an intensive lifestyle intervention (ILI) in overweight/obese individuals with type 2 diabetes. Methods: Weight losses and adherence (attendance, use of meal replacement products, and minutes of activity) were examined over one year of intervention in 2329 ILI participants in 209 treatment groups, which all received the same weight loss program. Results: Weight losses did not cluster among members of a treatment group (intra-class correlation [ICC] of 0.007), whereas measures of adherence had small/moderate clustering (ICCs of 0.05-0.11). The 209 groups varied in weight losses, with a mean of 8.64% (SD52.35%, interquartile range56.82%, 10.32%), but neither size nor baseline homogeneity of members affected the outcome. Conclusions: Although these findings suggest that it may not be necessary to control for clustering in behavioral weight loss studies, they also indicate that merely treating individuals in groups is not sufficient to harness social influences on weight loss.

Last Modified: 11/27/2014
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