Energy Balance and Obesity

This article describes the interplay among energy intake,energy expenditure, and body energy stores and illus-trates how an understanding of energy balance can help us develop strategies to reduce obesity. First, reducing obesity requires modifying both energy intake and energy expendi-ture, not simply focusing on either alone. Food restriction alone will not be effective in reducing obesity if human physiology is biased toward achieving energy balance at a high energy flux (ie, at a high level of energy intake and expenditure). In previous environments, a high energy flux was achieved with a high level of physical activity, but in today’s sedentary environment, it is increasingly achieved through weight gain. Matching energy intake to a high level of energy expenditure will likely be more feasible for most people than restricting food intake to meet a low level of energy expenditure. Second, from an energy balance point of