Different ethnic groups vary in susceptibility to obesogenic environments and to the adverse consequences of obesity, for both genetic/physiological and cultural/behavioural reasons. Effective interventions may also depend on the social and cultural context in which they are applied. The study of ethnic differences, and of the impacts of migration on specific population groups, may provide important mechanistic insights into pathways to obesity risk and its adverse consequences. Additionally, information on the propensities of different ethnic groups to obesity and its adverse consequences will be valuable for clinical decision-making.