OBJECTIVE It is widely recognised that South Asian men living in the UK are more likely to develop type 2 diabetes mellitus (T2DM) than their white British counterparts. Despite this, limited data have been published quantifying current dietary intake patterns and qualitatively exploring eating behaviours in this population. The objectives of this study were to (1) assess diet, (2) explore perceptions of T2DM, (3) investigate factors influencing eating behaviours in overweight/obese South Asian men and (4) determine the suitability of the UK Diet and Diabetes Questionnaire (UKDDQ) for use in this population. SETTING Community-based setting in the Greater London, UK area. PARTICIPANTS South Asian men aged 18-64 years, with a body mass index of over 23.0 kg/m2, not previously diagnosed with T2DM. METHODS A cross-sectional mixed-methods design, including assessment of dietary intake using UKDDQ (n=63), followed by semistructured interviews in a purposive sample (n=36). RESULTS UKDDQ scores indicated 54% of participants had a 'healthy' diet with a mean sample score of 3.44±0.43 out of a maximum of 5. Oily fish consumption was low (1.84±1.85). Body weight was positively associated with a high-added sugar subscore (r=0.253, p=0.047), with 69.8% of the men having 'unhealthy' intakes of sugar-sweetened beverages. Cultural commitments (eg, extended family and faith events), motivation and time were identified as key barriers to dietary change, with family support an important facilitator to making healthy dietary changes. Participants stated that UKDDQ was suitable for assessing diets of South Asians and made suggestions for tailoring questions related to rice consumption, providing examples of Indian sweets, and including ghee as a fat source. CONCLUSION Many of the areas of dietary improvement and factors affecting eating behaviours identified in this study are similar to those observed in the general UK population. Consumption of sugar-sweetened beverages in particular was high; given the association between their consumption and the risk of T2DM, this should be an area of primary focus for healthcare professionals. Nevertheless, there are sociocultural factors unique to this population that need to be considered when designing culturally specific programs to reduce the development of T2DM in this high-risk population.