The US obesity epidemic emerged in the late 1970s and affected every population group regardless of age, sex, or race.
1-3 Although the causes of the obesity epidemic remain controversial, such rapid changes must be due to environmental and behavioral changes such as diet, physical activity, or the built environment.
4,5 Genetic factors associated with adiposity may influence behavioral responses to environmental context (eg, by shaping appetite).
6,7 Thus, the environmental changes associated with the obesity epidemic may not have affected all individuals equivalently.