Obesity and Weight Management

Obesity is most commonly assessed using body mass index (BMI), a weight-to-height ratio with a threshold of 30 or above, though it has recognized limitations, since it cannot distinguish fat mass from muscle mass and its associated health risks vary somewhat by ethnicity and body composition. Waist circumference and waist-to-hip ratio are used alongside BMI to capture the distribution of body fat, since abdominal (visceral) adiposity carries greater metabolic risk than fat stored elsewhere. Obesity has multifactorial causes: twin and adoption studies indicate a substantial heritable component in individual susceptibility, while an increasingly "obesogenic" environment, characterized by ready availability of energy-dense food, larger portion sizes, and more sedentary daily life, shapes population-level trends. Its health consequences are extensive, including elevated risk of type 2 diabetes, cardiovascular disease, several cancers, osteoarthritis, and obstructive sleep apnea, along with reduced life expectancy on average.