Refugees face various nutritional challenges during and after migration. This cross-sectional, mixed-methods study seeks to investigate the prevalence of undernutrition and obesity among refugees in Geneva, and to identify barriers to healthy eating. Anthropometric measurements of 354 adult refugees were collected between 2017 and 2019 by trained nurses and dietitians. Seven focus group discussions totaling 51 participants, refugees and social workers, investigated conceptions and needs regarding diet. The mean Body Mass Index is 24.6 ± 4.8 kg/m2. Women are disproportionately affected by obesity compared to men (p < 0.001). Weight gain post-migration is correlated positively with length of stay in Geneva (p < 0.001). Major obstacles to healthy eating are economic and linguistic. For participants, cooking workshops and free physical activities are highly needed interventions. Post-migration lifestyle interventions should be implemented to prevent weight gain in this population. Such interventions must be multi-level, to overcome structural, social and behavioral barriers to healthy eating.