Determine the degree of obesity. In adults the body mass index (BMI) is a suitable measure. Mild obesity (BMI 25-30) does not usually necessitate treatment provided that the waist circumference is not too large. Treatment is usually indicated if the BMI exceeds 30. The more overweight the person is, the more active measures are necessary. Assess the extent of central obesity. The diagnosis is based on measuring waist circumference if the patient's BMI is in the range 25-30(-32). Weight reduction should be considered even in mild obesity (BMI 25-30) if the waist circumference exceeds 100 cm in men or 90 cm in women. Assess disorders associated with obesity. Treat the patient actively if he or she has a disease that is related to obesity and that can be alleviated by weight reduction. Consider the patient's age when planning the treatment. The younger the patient the more active the treatment should be. Patients above the age of 65 should be treated only if there are compelling indications.