Why do young kids become obese?
The causes are not yet fully understood. Both genes and the environment play a role.

The recent increase in obesity seems to be linked to environmental factors:
• people are much less active nowadays
• fatty and sugary foods are more accessible
• the average portion sizes have become larger
• the calories per mouthful have increased
Should kids ever be made to finish what's on their plate?
Don't force children to eat more when they say they are full - otherwise they could lose their ability to naturally regulate what they eat. Before serving up a second portion, wait a few minutes. It takes some time for the messages that tell us we have had enough to eat to reach the brain.
Can giving kids food as a reward cause obesity?
Using food as a reward is never a good idea because your child will learn to value certain 'treat' foods and may turn to food for comfort. Use non-food rewards instead – they don't need to be large material rewards. One of the best motivators is praise!
Should I tell my child off for being fat?
Your child may already feel upset about their weight. Telling them off will only make them feel worse and may add to the problem if they then turn to food for comfort. Don't single out your child as the one with the problem. The whole family can make healthy changes to their lifestyle.
Is it worth forbidding fattening foods?
Forbidding certain foods can make them seem more attractive. Teach your child about the health value of foods, particularly those that are rich in vitamins and nutrients. Make your home a healthy food zone. Fill up the fruit bowl instead of buying biscuits and crisps. Your child is likely to model themselves on your behaviour, so choose healthy food options whenever possible.
Should I offer my child a choice of food?
Research has shown that when there is more choice available we tend to eat more. Even the sight or smell of tempting food can override the body's natural mechanism of regulation so we eat when we're not hungry. You might want to offer your child a choice, but keep the options to a minimum.
Are 'weight management camps' a good way to treat obesity?
They can be. One of the problems is keeping that weight off. If the child comes home and none of the family members have altered their eating habits, improvements may be difficult to sustain.
When would you recommend surgery to tackle obesity?
If a child has massive obesity and his or her health is being put at serious risk, then all options have to be considered. Surgical treatments have shown good results in adults, but there are serious risks. Performing surgery on children would raise some difficult issues.
At what age should kids be treated for obesity?
Parents of even young children can make sure the family changes to a healthy lifestyle rather than targeting weight loss specifically. Children grow at different rates and many overweight children will 'grow out of it' as they grow taller. Few treatments are targeted at children under the age of seven years. From age eight to 10, a child who is obese should have a medical evaluation to assess the severity of the problem. The older your child is, the less likely they are to grow out of it. A 15-year-old who is overweight is likely to remain so in adulthood.
Professor Jane Wardle is the Director of the Health Behaviour Unit at University College, London.