Obesity means having too much body fat. It is different from being overweight, which means weighing too much. The weight may come from muscle, bone, fat, and/or body water. Both terms mean that a person’s weight is greater than what’s considered healthy for his or her height.

Obesity occurs over time when a person eats more calories than are used by the body. The balance between calories-in and calories-out differs for each person. Factors that might affect an individual’s weight include genetic makeup, overeating, eating high-fat foods, and not being physically active. Being obese increases the risk of diabetes, heart disease, stroke, arthritis, and some cancers.

Obesity can lead to many other medical complications.

Diagnosis and Treatment

Diagnosis of obesity involves measuring an individual’s body fat in comparison with his or her height. Losing even 5 to 10 percent of body weight can delay or prevent some of the diseases and complications associated with obesity. For example, that means losing 10 to 20 pounds if a person weighs 200 pounds. The major treatment for obesity is a change of eating and exercise habits to balance caloric intake with calories used.