High obesity prevalence persists as a major issue for societies globally. Chronic overweight and obesity have high health, social, and economic costs, and the benefits of achieving and maintaining healthy weight for overall health and well-being are well established. Obesity in children and adolescents is of particular concern because it may compromise physical and psychosocial development and set the stage for early onset of adverse health effects that accumulate over a lifetime. Relevant to the topic of this discussion paper, obesity is also a health equity issue. Social disadvantage tends to intensify the exposure to obesity-promoting influences. The challenge of preventing and controlling obesity includes the need to assure that socially disadvantaged populations benefit from relevant public health interventions.
Population-wide obesity and its health consequences are linked to eating and physical activity patterns that have become ways of life in modern societies. This is a global problem, but one for which solutions must be tailored to national and subnational contexts. Human physiologic systems for regulation of food intake are well developed for responding to hunger but poorly developed for curbing overeating, and they evolved when routine physical activity levels were much higher than they are now. Thus, it is often said that from an evolutionary perspective widespread obesity reflects a natural response to an unnatural environment. On the energy intake side, this unnatural environment is characterized by ubiquitous, heavily advertised, and highly palatable high-calorie foods and beverages and large portions of restaurant meals; these all promote caloric overconsumption. On the energy output side, the unnatural environment is evident in residential areas where cars are a common form of transportation or where mobility depends on using a car, in sedentary work environments that limit physical activity, and where sedentary entertainment is readily available, affordable, and heavily promoted.