Obesity in child should not be overlooked. It is an important problem of the world. Many countries in the world such as USA, Australia, Mexico, Africa, and Thailand have this problem. Most children in Thailand are overweighted. There are many researches indicates that obesity in child has increased drastically in the past few years. What is obesity? Obesity is the condition when the body has too much fat which resulted in overweighted problems, usually occurred in a child aged around 5-11 years old. Obesity in child is a risk to their health such as blood pressure, diabetes, heart disease, etc. Causes of obesity in child are endogenous obesity and exogenous obesity,but main cause is exogenous obesity. There are three reasons of obesity in child which are: lack of exercise, consume too much junk food and do not control diets.