Obesity

Obesity, characterized by excess fat stores, constitutes a major risk for many diseases, especially diabetes. Obesity is currently defined as a body mass index >30. The prevalence of obesity has increased dramatically since 1980, leading some to refer to an obesity epidemic, which may constitute the greatest threat to public health in the twenty-first century. Fat stores are determined by the balance of food intake and energy expenditure. Largely this balance is regulated by hypothalamic neurons that monitor nutritional status by sensing blood levels of leptin, which reflect fat stores, and nutrients such as glucose, which reflect short-term nutrient state. Currently, the only effective treatment for obesity is gastric bypass surgery.