Obesity is defined as a body mass index (BMI) greater than the 95th percentile for age and gender.

• Although genetics and some disorders cause obesity, most adolescent obesity results from a lack of physical activity and overeating.
• The diagnosis is based on a BMI over the 95th percentile.
• Eating a nutritious diet, moving more, and going to counseling help treat obesity.

Obesity is twice as common among adolescents as it was 30 years ago. Although most of the complications of obesity occur in adulthood (see Obesity and the Metabolic Syndrome: Obesity), obese adolescents are more likely than their peers to have high blood pressure and type 2 diabetes. Although fewer than one third of obese adults were obese as adolescents, most obese adolescents remain obese in adulthood.

The factors that influence obesity among adolescents are the same as those among adults. Parents often are concerned that obesity is the result of some type of endocrine disease, such as hypothyroidism or hyperadrenocorticism, but such disorders are rarely the cause. Adolescents with weight gain caused by endocrine disorders are usually of small stature and have other signs of the underlying disorder. An adolescent who is short and has high blood pressure should be tested for Cushing's syndrome (see Adrenal Gland Disorders: Cushing Syndrome). Although genetic influences are common and responsible genes are now being identified, most obese adolescents simply consume more calories than they burn. Because of society's stigma against obesity, many obese adolescents have a poor self-image and become increasingly sedentary and socially isolated.

Intervention for obese adolescents should be focused on developing healthy eating and exercise habits rather than on losing a specific amount of weight. Caloric intake is reduced by

• Establishing a well-balanced diet of ordinary foods
• Making permanent changes in eating habits

Calorie burning is increased by

• Increasing physical activity

Summer camps for obese adolescents usually help them lose a significant amount of weight, but without continuing effort, the weight usually is regained. Counseling to help adolescents cope with their problems, including poor self-esteem, may be helpful.

Drugs that help reduce weight are generally not used during adolescence because of concerns about safety and possible abuse. One exception is for obese adolescents with a strong family history of type 2 diabetes. They are at high risk of developing diabetes. The drug metforminSome Trade Names
GLUCOPHAGE
, which is used to treat diabetes, may help them lose weight and also lower their risk of becoming diabetic.

Last full review/revision January 2009 by Sharon Levy, MD, MPH