This chapter discusses maintaining a healthy weight and defines overweight and obesity. It notes that overweight is defined as 1-19% above desirable weight based on gender, age and frame size, while obesity is 20% or more above desirable weight. The chapter then discusses rates of overweight and obesity in the US and health risks associated with excess weight like hypertension, heart disease and diabetes. It also covers methods of measuring weight and body composition including BMI, body fat percentage, and tools like electrical impedance, Bod Pod and hydrostatic weighing. The causes of obesity discussed include calorie balance, genetics, hormones, family and social/cultural factors. Weight management strategies covered include diet, exercise, drugs and surgery. Eating disorders like anore