In many ways, childhood obesity is a puzzling disease. Doctors do not fully understand how the body controls weight and body fat. On one hand, the cause seems simple. If a person takes in more calories than they use for energy, then they will gain weight.

But a teen's obesity can be caused by a combination of things. It can be linked to:

• Genes
• Socioeconomic issues
• How the body turns food into energy (metabolism)
• Not getting enough sleep
• Lifestyle choices
• Emotional issues

Some endocrine disorders, diseases, and medicines may also have a strong effect on a child’s weight.

Things that may put your teen at risk for obesity are:

• Genes. Obesity may be passed down through families. Having even one obese parent may raise a child’s risk for it. Experts are looking at the link between genes, the ever-changing environment, and obesity.
• Metabolism. Each person’s body uses energy differently. Metabolism and hormones don’t affect everyone the same way. They 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 more common among low-income people. In some places, people may have limited access to affordable healthy foods. Or they may not have a safe place to exercise.
• Lifestyle choices. Overeating and an inactive lifestyle both contribute to obesity. A diet full of sugary, high-fat, and refined foods can lead to weight gain. So can a lack of regular exercise. In children, watching TV and sitting at a computer can play a part.

Too much body fat is the main symptom of obesity. But it’s hard to directly measure body fat. A guideline called the body mass index (BMI) is used to estimate it. The BMI uses a teen’s weight and height to come up with a result. The result is then compared with standards for children of the same gender between the ages of 2 and 20.

A teen who is overweight has a BMI between the 85th and 95th percentile for age and gender. They are obese if the BMI is greater than the 95th percentile for age and gender.

Obesity is diagnosed by a healthcare provider. BMI is often used to define obesity in teens. It has 2 categories:

• BMI at the 95th percentile or more for age and gender, or BMI of more than 30, whichever is smaller. BMI findings in this category mean the child should have a full health checkup.
• BMI between the 85th and 95th percentile, or BMI equal to 30, whichever is smaller. This result means the child should have a screening that looks at 5 areas of health risk:
  • Family history of cardiovascular disease, high cholesterol, diabetes, and obesity
  • High blood pressure
  • Total cholesterol level
  • Large gains in BMI from year to year
  • Concerns about weight, including the child’s own concerns about being overweight

Treatment depends on your teen’s symptoms, age, and health. It also depends on how severe the condition is.

Treatment for obesity may include:

• Diet counseling
• Changes to diet and number of calories eaten
• More physical activity or an exercise program
• Behavior changes
• Individual or group therapy that focuses on changing behaviors and facing feelings linked to weight and normal developmental issues
• Support and encouragement for making changes and following recommended treatments

Treatment often involves the help of a nutritionist, mental health professionals, and an exercise specialist. Your teen’s treatment goals should be realistic. They should focus on a modest cutting back of calories, changing eating habits, and adding more physical activity.

Obesity can affect your teen’s health in a number of ways. These include:

• High blood pressure and high cholesterol. These are risk factors for heart disease.
• Diabetes. Obesity is the major cause of type 2 diabetes. It can cause resistance to insulin, the hormone that controls blood sugar. When obesity causes insulin resistance, blood sugar becomes higher than normal.
• Joint problems, such as osteoarthritis. Obesity can affect the knees and hips because of the stress placed on the joints by extra weight.
• Sleep apnea and breathing 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 breathing 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. They may be blamed for their condition. They may be seen as lazy or weak-willed. Obese children can have low self-esteem that affects their social life and emotional health.

Young people often become overweight or obese because they have poor eating habits and aren’t active enough. Genes also play a role.

Here are some tips to help your teen stay at a healthy weight:

• Focus on the whole family. Slowly work to change your family’s eating habits and activity levels. Don’t focus on a child’s weight.
• Be a role model. Parents who eat healthy foods and are physically active set an example. Their child is more likely to do the same.
• Encourage physical activity. Children should get at least 60 minutes of physical activity each day.
• Limit screen time. Cut your teen’s screen time to less than 2 hours a day in front of the TV and computer.
• Have healthy snacks on hand. Keep the refrigerator stocked with fat-free or low-fat milk instead of soft drinks. Offer fresh fruit and vegetables instead of snacks high in sugar and fat.
• Aim for 5 or more. Serve at least 5 servings of fruits and vegetables each day.
• Drink more water. Encourage teens to have water instead of drinks with added sugar. Limit your child’s intake of soft drinks, sports drinks, and fruit juice drinks.
• Get enough sleep. Encourage teens to get more sleep every night. Earlier bedtimes have been found to decrease rates of obesity.