We examined self-determination theory (SDT) and weight loss, and hypothesized that the Diabetes Prevention Program's (DPP) intervention would result in an increase in autonomous regulation of motivation (AR) in participants. Further, that those with higher AR, and those who perceived educators as supporting SDT-defined needs, would lose more weight. Support, Health Information, Nutrition and Exercise (SHINE) Study data (N = 257) were analyzed. SHINE was a randomized, controlled DPP translation trial (2-years, telephonic, primary care staff). Autonomous motivation in males increased significantly, while females showed no change. Males with high AR, but not females, lost more weight. However, the significance of these relationships varied over time. Participants who perceived educators as more supportive of psychological needs lost more weight (especially males). However, effect of support on weight loss was not mediated by AR change. Autonomous motivation and educator support are relevant to male weight loss. Future research might develop interventions to enhance autonomous motivation and educator support, and understand change pathways.