Not all children carrying extra pounds are overweight or obese. Some children have larger than average body frames. And children normally carry different amounts of body fat at the various stages of development. So you might not know by how your child looks if weight is a health concern.

The body mass index (BMI), which provides a guideline of weight in relation to height, is the accepted measure of overweight and obesity. Your child's doctor can use growth charts, the BMI and, if necessary, other tests to help you figure out if your child's weight could pose health problems.

Lifestyle issues — too little activity and too many calories from food and drinks — are the main contributors to childhood obesity. But genetic and hormonal factors might play a role as well. For example, recent research has found that changes in digestive hormones can affect the signals that let you know you're full.

Many factors — usually working in combination — increase your child's risk of becoming overweight:

• Diet. Regularly eating high-calorie foods, such as fast foods, baked goods and vending machine snacks, can cause your child to gain weight. Candy and desserts also can cause weight gain, and more and more evidence points to sugary drinks, including fruit juices, as culprits in obesity in some people.
• Lack of exercise. Children who don't exercise much are more likely to gain weight because they don't burn as many calories. Too much time spent in sedentary activities, such as watching television or playing video games, also contributes to the problem.
• Family factors. If your child comes from a family of overweight people, he or she may be more likely to put on weight. This is especially true in an environment where high-calorie foods are always available and physical activity isn't encouraged.
• Psychological factors. Personal, parental and family stress can increase a child's risk of obesity. Some children overeat to cope with problems or to deal with emotions, such as stress, or to fight boredom. Their parents might have similar tendencies.
• Socioeconomic factors. People in some communities have limited resources and limited access to supermarkets. As a result, they might buy convenience foods that don't spoil quickly, such as frozen meals, crackers and cookies. Also, people who live in lower income neighborhoods might not have access to a safe place to exercise.

Childhood obesity can have complications for your child's physical, social and emotional well-being.

Physical complications

• Type 2 diabetes. This chronic condition affects the way your child's body uses sugar (glucose). Obesity and a sedentary lifestyle increase the risk of type 2 diabetes.
• Metabolic syndrome. This cluster of conditions can put your child at risk of heart disease, diabetes or other health problems. Conditions include high blood pressure, high blood sugar, high triglycerides, low HDL ("good") cholesterol and excess abdominal fat.
• High cholesterol and high blood pressure. A poor diet can cause your child to develop one or both of these conditions. These factors can contribute to the buildup of plaques in the arteries, which can cause arteries to narrow and harden, possibly leading to a heart attack or stroke later in life.
• Asthma. Children who are overweight or obese might be more likely to have asthma.
• Sleep disorders. Obstructive sleep apnea is a potentially serious disorder in which a child's breathing repeatedly stops and starts during sleep.
• Nonalcoholic fatty liver disease (NAFLD). This disorder, which usually causes no symptoms, causes fatty deposits to build up in the liver. NAFLD can lead to scarring and liver damage.
• Bone fractures. Obese children are more likely to break bones than are children of normal weight.

Social and emotional complications

• Low self-esteem and being bullied. Children often tease or bully their overweight peers, who suffer a loss of self-esteem and an increased risk of depression as a result.
• Behavior and learning problems. Overweight children tend to have more anxiety and poorer social skills than normal-weight children do. These problems might lead children who are overweight either to act out and disrupt their classrooms or to withdraw socially.
• Depression. Low self-esteem can create overwhelming feelings of hopelessness, which can lead to depression in some children who are overweigh