While most children should not be put on a severely restricted diet, weight management by a combined approach of a sensible diet and regular exercise will help to control their weight gain.
Children normally need a certain number of calories each day (energy allowance) that their bodies use as energy for normal daily activities (walking, breathing, etc.). This ranges for boys from 2000 calories for a 7-10 year old, 2500 calories for an 11-14 year old, and 3000 calories for a 15-18 year old. For girls the ranges are from 2000 calories for a 7-10 year old, to 2200 calories for an 11-18 year old. These are only estimates and some children need more (fast metabolism) or less (slow metabolism) of an energy allowance for daily activities.
If a child consumes more food and calories than is required by their energy allowance, than those excess calories are converted to fat for storage. Conversely, if a child consumes less food and calories than is required by their energy allowance, than their body fat is converted to energy for the needed calories.
Energy Stored (Fat) = Energy In - Energy Used
You can lose weight by either dieting (eating fewer calories each day) or by exercising, so that your body needs more energy and uses up more calories. Either way, body fat will be burned and converted to energy and you will lose weight.
The first goal of weight management in kids should be to stop weight gain and maintain normal growth in height. This way they can 'grow into' their weight. You can begin doing this by having your child eat healthier (about 500 fewer calories each day) and begin a program of regular exercise and physical activity. Once your child has stopped gaining weight and is on a regular program of dieting and exercising, you can set further goals of slow weight loss (about a 10% reduction at a time) if necessary.