Bad or unhealthy diets and lack of exercise cause obesity
Eating right and exercising regularly can help you avoid excess weight gain and maintain a healthy weight.
There are many health problems which can be caused by obesity.
Coronary heart disease, diabetes, and damage to weight-bearing joints (such as your knees) are the main ones.
Social problems are probably worse for kids...
Who wants to be called bad names?
Who wants to be left out of games and teams?
Who wants to have a hard time finding friends?
If a friend has a problem with obesity, then you can be a good friend by...
eating good stuff yourself and encouraging them to do the same
playing together in an active way
getting them to join in sports lessons by encouragement
helping them to practice sports skills
doing something active together after school, like walking the dog or bike riding, rather than watching TV or playing video games.
telling the teacher if your friend is being teased or called unkind names - this is a type of bullying that no one should have to suffer
saying nice things about the things they do that you think are great - such as a nice smile, skills such as playing a musical instrument or being good at sports.
Adapted from http://www.cyh.com/HealthTopics/HealthTopicDetailsKids.aspx?p=335&np=152&id=2462