Influence of family, friend and coworker social support and social undermining on weight gain prevention among adults.

OBJECTIVE Examine longitudinal associations between sources of social support and social undermining for healthy eating and physical activity and weight change. METHODS Data are from 633 employed adults participating in a cluster-randomized multilevel weight gain prevention intervention. Primary predictors included social support and social undermining for two types of behaviors (healthy eating and physical activity) from three sources (family, friends, and coworkers) obtained via self-administered surveys. The primary outcome (weight in kg) was measured by trained staff. Data were collected at baseline, 12 months, and 24 months. Linear multivariable models examined the association of support and social undermining with weight over time, adjusting for intervention status, time, gender, age, education, and clustering of individuals within schools. RESULTS Adjusting for all primary predictors and covariates, friend support for healthy eating (β = -0.15), coworker support for healthy eating (β = -0.11), and family support for physical activity (β = -0.032) were associated with weight reduction at 24 months (P-values<0.05). Family social undermining for healthy eating was associated with weight gain at 24 months (β = 0.12; P = 0.0019). CONCLUSIONS Among adult employees, friend and coworker support for healthy eating and family support for physical activity predicted improved weight management. Interventions that help adults navigate family social undermining of healthy eating are warranted.