Obesity is diagnosed when an individual's body mass index (BMI) is 30 or higher. Your body mass index is calculated by dividing your weight in kilograms (kg) by your height in meters (m) squared.

BMI Weight status
Below 18.5 Underweight
18.5 — 24.9 Normal
25.0 — 29.9 Overweight
30.0 and higher Obese
40.0 and higher Extreme obesity

Because BMI doesn't directly measure body fat, some people, such as muscular athletes, may have a BMI in the obese category even though they don't have excess body fat.

When to see a doctor

If you think you may be obese, and especially if you're concerned about weight-related health problems, see your doctor or health care provider. You and your doctor can evaluate your health risks and discuss your weight-loss options. Even modest weight loss can lessen or prevent problems related to obesity. Weight loss is usually possible through dietary changes, increased physical activity and behavior changes. In some cases, prescription medications or weight-loss surgery may be options.

Jun. 07, 2013