The past two decades have seen a dramatic increase in the prevalence of obesity in the US population. Although increasing obesity was observed in every sociodemographic group, at every point in time groups with lower education, African Americans and Native Americans, and women in lower income households had higher rates of obesity and related chronic conditions such as diabetes. Also noteworthy is the much faster increase of severe obesity compared with moderate obesity, which added further strain to the health care system and proved especially challenging to health care providers. We provide data on the populationwide trends in weight gain, economic consequences of health care cost growth and the socioeconomic disparities in obesity and diabetes. We further di scuss the socioeconomic and environmental changes that are likely underlying mechanisms for the obesity epidemic and related disparities. We conclude the chapter by discussing implications of these trends for the prevention and treatment of diabetes and challenges and opportunities faced by the health care system and providers.