Although genetics and some disorders cause obesity, most adolescent obesity results from a lack of physical activity and consuming more calories than needed for activity level.
The diagnosis is based on a BMI at or over the 95th percentile for age and gender.
Eating a nutritious diet and increasing exercise help treat obesity, and some children may be given medication for weight loss or weight-loss surgery.
Obesity is defined by the body mass index Obesity 
(BMI). Adolescents whose BMI is in the top 5% for their age and gender are considered to have obesity. Being in the top 5% means their BMI is higher than 95% of their peers (at or over the 95th percentile).
Obesity Obesity Obesity is excess body weight. Obesity is influenced by a combination of factors, which usually results in consuming more calories than the body needs. These factors may include physical inactivity... read more is twice as common among adolescents as it was 30 years ago. Although most of the complications of obesity occur in adulthood, adolescents with obesity are more likely than their peers to have high blood pressure and type 2 diabetes Type 2 diabetes Diabetes mellitus is a disorder in which blood sugar (glucose) levels are abnormally high because the body does not produce enough insulin or fails to respond normally to the insulin produced... read more 
. Although fewer than one third of adults with obesity were obese as adolescents, most adolescents with obesity become adults with obesity.
Despite many treatment approaches, obesity is one of the most difficult problems to treat, and long-term success rates remain low.
(See also Introduction to Problems in Adolescents Introduction to Problems in Adolescents For most children, adolescence is a period of good physical health. The most common problems during adolescence relate to Growth and development School Childhood illnesses that continue into... read more .)
Causes of Obesity in Adolescents
The factors that influence obesity among adolescents are the same as those among adults.
Hormonal disorders, such as an underactive thyroid gland (hypothyroidism Hypothyroidism Hypothyroidism is underactivity of the thyroid gland that leads to inadequate production of thyroid hormones and a slowing of vital body functions. Facial expressions become dull, the voice... read more 
) or overactive adrenal glands, may result in obesity but are rarely the cause. Adolescents with weight gain caused by hormonal disorders are usually short and most often have other signs of the underlying disorder. Any adolescent with obesity who is short and has high blood pressure should be tested for the hormonal disorder Cushing syndrome Cushing Syndrome In Cushing syndrome, the level of corticosteroids is excessive, usually due to taking corticosteroid drugs or overproduction by the adrenal glands. Cushing syndrome usually results from taking... read more 
.
Genetics play a role, which means that some people are at greater risk of obesity than others, and obesity may be more common among members of the same family.
Because of society’s stigma against obesity, many adolescents with obesity have a poor self-image and may become socially isolated.
Treatment of Obesity in Adolescents
Healthy eating and exercise habits
For adolescents 12 years old and older with a BMI at or over the 95th percentile, weight-loss medications
For adolescents 13 years old and older with a BMI significantly over the 95th percentile, evaluation for weight-loss surgery
All children and adolescents with obesity are given intensive strategies to help them develop healthy eating and exercise habits and make changes to their health behavior.
Reducing calorie intake and burning calories are two ways to meet these goals.
Calorie 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
Adolescents 12 years old and older with obesity (BMI at or over the 95th percentile for age and gender) may be given medications for weight loss.
Adolescents 13 years old and older with severe obesity (BMI significantly above the 95th percentile for age and gender) may be referred to a surgeon who specializes in this area for a full evaluation for weight-loss surgery (bariatric surgery Bariatric Surgery Bariatric (weight-loss) surgery alters the stomach, intestine, or both to produce weight loss. In the United States, about 160,000 people have bariatric surgery each year. This number accounts... read more ).
Counseling to help adolescents cope with social problems, including poor self-esteem, may be helpful.
