Children's Hospital


Obesity in Adolescents

What is obesity?

Obesity is a serious, long-term (chronic) disease. Overweight and obesity refer to having too much body fat. But it’s difficult to directly measure body fat, so a guideline called the body mass index (BMI) is used to estimate it. The BMI uses the weight and height of a child to come up with a result. The result is compared with standards for children of the same gender between the ages of 2 and 20 years. 

Photo of overweight teen

Overweight is defined as having a BMI between the 85th and 95th percentile for age and gender. Obesity is defined as greater than the 95th percentile for age and gender.

What causes obesity?

In many ways, childhood obesity is a puzzling disease. How the body regulates weight and body fat is not well understood. On one hand, the cause appears to be simple. If a person takes in more calories than he or she uses for energy, then he or she will gain weight.

But the risk factors that lead to childhood obesity can be a complex combination of factors. They include genes, socioeconomic factors, metabolism, and lifestyle choices. Some endocrine disorders, diseases, and medicines may also have a powerful effect on a child's weight. Obesity is more common among American Indian, black, and Mexican Americans than in non-Hispanic whites.

Factors that may affect obesity include:

  • Genes. Studies have shown that a tendency to be obese can be passed down through families. Most research is trying to better understand the link between these genes, the ever-changing environment, and obesity. Having even one obese parent raises a child's risk for obesity.

  • Metabolic factors. How a particular person’s body uses energy is different from how someone else's body uses energy. Metabolism and hormones do not affect everyone the same way. But these factors may play a role in weight gain in children and teens

  • Socioeconomic factors. There is a strong tie between economic status and obesity. Obesity is also more common among low-income people.

  • Lifestyle choices. Overeating and a sedentary lifestyle both contribute to obesity. These are lifestyle choices that can be changed:

    • A diet full of sugary, high-fat, and refined foods can lead to weight gain. And as more U.S. families eat on-the-go, they often choose high-calorie foods and beverages. And some people have limited access to affordable healthy foods.

    • Lack of regular exercise contributes to obesity in adults. It makes it difficult to maintain weight loss. In children, watching television, sitting at a computer, and other sedentary activities contribute to obesity. In some communities children may not have a safe place to exercise.

Health effects of obesity

Obesity can affect health in a number of ways. Each year obesity-related health conditions cost billions of dollars and cause premature deaths in the U.S. The health effects tied to obesity include:

  • High blood pressure and high cholesterol.  These are a risk factors for heart disease. 

  • Diabetes. Obesity is the major cause of type 2 diabetes. Obesity can cause resistance to insulin, the hormone that regulates blood sugar. When obesity causes insulin resistance, blood sugar becomes higher than normal. Even moderate obesity greatly increases the risk for diabetes.

  • Joint problems, including osteoarthritis. Obesity can affect the knees and hips because of the stress placed on the joints by extra weight.

  • Sleep apnea and respiratory problems. Sleep apnea causes people to stop breathing for brief periods. It interrupts sleep throughout the night and causes sleepiness during the day. It also causes heavy snoring. The risk for other respiratory problems such as asthma is higher in an obese child.

  • Psychosocial effects. Modern culture often sees overly thin people as the ideal in body size. Because of this, people who are overweight or obese often suffer disadvantages. Overweight and obese people are often blamed for their condition. They may be considered to be lazy or weak-willed. Obese children can have low self-esteem that affects their social life and emotional health. 

How is obesity diagnosed?

Obesity is diagnosed by a doctor. BMI is usually used to define obesity in adolescents. Two categories are defined:

  1. BMIs at the 95th percentile or more for age and sex, or BMIs of more than 30, whichever is smaller. BMI findings in this category mean the child should have a complete health checkup.

  2. BMIs between the 85th and 95th percentile, or BMIs equal to 30, whichever is smaller. This means the child should have screening that includes a look at five areas of health risk:

    • Family history of cardiovascular disease, high cholesterol, diabetes, and obesity

    • High blood pressure

    • Total cholesterol level

    • Large increases in BMI from year to year

    • Concerns about weight. This includes the child's concerns about himself or herself as being overweight.

Treatment for obesity

Treatment will depend on your child’s symptoms, age, and general health. It will also depend on how severe the condition is.

Treatment for obesity in adolescents may include:

  • Diet counseling

  • Changes to diet and amount of calories eaten

  • Increased exercise or taking part in an appropriate exercise program

  • Behavior changes

  • Individual or group therapy that focuses on changing behaviors and confronting feelings related to weight and normal developmental issues

  • Support and encouragement for making changes and following recommended treatments

Treatment often includes the help of a nutritionist, mental health professionals, and an exercise specialist. Your child's treatment goals should be realistic. They should focus on a modest cutting back of calories, changing eating habits, and adding a healthy exercise-oriented lifestyle.

Preventing obesity

Young people generally become overweight or obese because they have poor eating habits and they don't get enough physical activity. Genes and lifestyle also contribute to a child's weight status.

Here are tips to help prevent overweight and obesity during childhood and adolescence:

  • Gradually work to change family eating habits and activity levels rather than focusing on a child's weight.

  • Be a role model. Parents who eat healthy foods and are physically active set an example so that a child is more likely to do the same.

  • Encourage physical activity. Children should get at least 60 minutes of  physical activity every day 

  • Reduce "screen" time in front of the television and computer to less than 2 hours a day.

  • Keep the refrigerator stocked with fat-free or low-fat milk and fresh fruit and vegetables instead of soft drinks and snacks high in sugar and fat.

  • Serve at least 5 servings of fruits and vegetables each day.

  • Encourage children to drink water instead of beverages with added sugar, such as soft drinks, sports drinks, and fruit juice drinks. 

Online Medical Reviewer: Godsey, Cynthia, MSN, APRN, MSHE, FNP-BC
Online Medical Reviewer: Pierce-Smith, Daphne, RN, MSN, CCRC
Last Review Date: 2/9/2016
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