Dyadic collaboration in shared health behavior change: the effects of a randomized trial to test a lifestyle intervention for high-risk Latinas.

Objective: This study sought to evaluate the feasibility of a pilot, dyad-based lifestyle intervention, the Unidas por la Vida program, for improving weight loss and dietary intake among high-risk Mexican American mothers who have Type 2 diabetes and their overweight/obese adult daughters.

Method: Mother-daughter dyads (N = 89) were recruited from two federally qualified health centers and randomly assigned to either the Unidas intervention or to the control condition. The 16-week Unidas intervention consisted of the following: (a) four group meetings, (b) eight home visits, and (c) booster telephone calls by a lifestyle community coach. The control condition consisted of educational materials mailed to participants' homes. Participants completed surveys at T1 (baseline) and T2 (16 weeks) that assessed various demographic, social network involvement, and dietary variables.

Results: Unidas participants lost significantly more weight at T2 (p < .003) compared with the control participants. Furthermore, intervention participants also were more likely to be eating foods with lower glycemic load (p < .001) and less saturated fat (p = .004) at T2. Unidas participants also reported a significant increase in health-related social support and social control (persuasion control only) and a decrease in undermining.

Conclusions: The Unidas program promoted weight loss and improved dietary intake, as well as changes in diet-related involvement of participants' social networks. The results from this study demonstrate that interventions that draw upon multiple people who share a health-risk have the potential to foster significant changes in lifestyle behaviors and in social network members' health-related involvement. Future research that builds on these findings is needed to elucidate the specific dyadic and social network processes that may drive health behavior change.