Obesity in children and teens (meaning a BMI-for-age above the 95th percentile) can occur as a result of different combinations of reasons, including environmental and genetic factors. However, it's important to realise that weight gain, whether leading to mild or severe clinical obesity, typically occurs only when a person consumes more calories than he/she expends. A large calorie surplus is typically needed to cause obesity.There is an epidemic of childhood obesity in the United States and throughout the world. Experts estimate one in five children between the ages of 6 and 17 are overweight. Millions of these children face a higher risk much earlier in life of developing obesity-related disorders, such as diabetes and heart disease.Studies have shown obese children have an exceptionally hard time losing weight and following through with lifestyle changes in adulthood when their health, and even their lives, may depend on them – all the more reason why parents should encourage kids to remain physically active throughout childhood.Childhood obesity is the result of an interaction between food, state of mind, family and the environment.An imbalance between intake and output. Intake: excessive consumption of fast foods and unhealthy food choices. Output: less time spent playing outside, more time spent on a computer, playing video games or watching TV.The Family. The risk of becoming obese is greatest among children who have two obese parents. This may be due to powerful genetic factors, the manner in which the child is raised, parental modeling of both eating and exercise behaviors. One half of parents of elementary school children never exercise vigorously.Low-energy Expenditure. The average American child spends several hours each day watching television; time which in previous years might have been devoted to physical pursuits. Obesity is greater among children and adolescents who frequently watch television, not only because little energy is expended while viewing but also because of simultaneous consumption of high-calorie snacks. Only about one-third of elementary children have daily physical education, and less than than one-fifth have extracurricular physical activity programs at their schools. The American Academy of Pediatrics urges parents to take walks or otherwise get physical with their children at least once a week, to make up for shrinking levels of physical education in schools.Diet ManagementFasting or extreme caloric restriction is not advisable for children. Not only is this approach psychologically stressful, but it may adversely affect growth and the child's perception of "normal" eating. Balanced diets with moderate caloric restriction, especially reduced dietary fat, have been used successfully in treating obesity (Dietz, 1983). Nutrition education may be necessary. Diet management coupled with exercise is an effective treatment for childhood obesity (Wolf et al., 1985). Prevention of Childhood ObesityParent education is one of the best ways to prevent obesity in children. Preventing obesity is far easier than treating it. Parent education should focus on promotion of breastfeeding, recognition of signals of satiety, selection of low-fat snacks, good exercise habits and monitoring of television viewing.