Effect of group racial composition on weight loss in African Americans

We do not know how racial composition of a group influences behavior change for African Americans (AAs) in group-based weight loss programs. We tested the hypothesis that AA who participate in all AA weight loss intervention groups will lose more weight than AA who participate in mixed race groups.

This observational study was ancillary to Phase 1 of the Weight Loss Maintenance Study, a multi-center trial of strategies to maintain weight loss after a 20-week behavior modification program. Three of four centers recruited several all-AA intervention groups. Remaining groups were combinations of AA and non-AA participants. All participants received the same weight loss intervention. Change in weight was the primary outcome, comparing participants of all-AA groups with AA participants of mixed race groups conducted by the same AA interventionists. Secondary outcomes included measures of intervention adherence and behavior change.

Participants of all-AA groups (n = 271) were comparable to other AA participants (n = 106). The mean proportion of AA in mixed race groups was 56%. All-AA group participants had similar weight loss as those in mixed groups (-4.2 vs. -4.2 kg, P = 0.97). There were no differences between the groups in mean number of sessions attended or changes in dietary intake.

Significant weight loss was observed in both groups, with no effect of group composition on adherence or weight loss outcomes. Special logistics to accommodate all-AA groups may not be necessary. Despite varying instructional environments, AA appeared to respond positively to intervention messages with significant changes in dietary intake, physical activity (PA), and weight.