Most people have difficulty maintaining a healthy diet. Both social and individual factors play a role in shaping one's diet, and individual factors might be differentially associated with eating depending on social conditions. The present research focuses on eating to regulate emotion and body weight in the context of couple relationships. Forty-three committed heterosexual couples reported on emotion-regulation strategies including the use of eating to regulate emotion (ERE). During a lab visit, participants discussed their health habits with their partners and their body composition was measured (e.g.: weight, height, percent body fat). Finally, participants completed daily diaries assessing their emotions as well as their food intake relative to their own normal eating. I first tested whether ERE was associated with other measures of emotion regulation as well as body composition at an individual level. As predicted, ERE demonstrated internal consistency, was moderately correlated with an established measure of emotion-eating, and uncorrelated with other measures of emotion regulation. High ERE was associated with higher body mass index, as well as higher waist circumference and percent body fat among older women, and with higher percent body fat among younger men. Secondly, I tested whether self-reported ERE predicted connections between daily emotional fluctuations and eating. Consistent with my hypothesis, those who reported high ERE ate worse when they experienced negative emotions or did not eat better when they experienced positive ones (which was the case among people with low ERE). Finally, I tested whether ERE in couples was associated with body composition under specific relationship conditions. As predicted, when both partners had high ERE, women who used more we-talk during a discussion of health habits also had higher BMI. However, women who used high I-talk in such couples had lower BMI despite having high ERE. Moreover, in such couples expression of negative emotion by partners was associated with higher BMI. Identifying individual and couple-level factors shaping dietary practices adds to development of interventions for poor health habits. It is an important step in shifting disease-focused models of medical care towards more comprehensive, patient-centered care.