What is a healthy weight for a child?

Obesity is easier to prevent than to treat, and prevention focuses in large measure on parent education. In infancy, parent education should center on promotion of breastfeeding, recognition of signals of satiety, and delayed introduction of solid foods. In early childhood, education should include proper nutrition, selection of low-fat snacks, good exercise/activity habits, and monitoring of television viewing. In cases where preventive measures cannot totally overcome the influence of hereditary factors, parent education should focus on building self-esteem and address psychological issues.

You may find it difficult to tell whether your child has temporary "puppy fat" or is genuinely overweight. In adults, a simple formula (the body mass index, or BMI) is used to work out whether a person is the right weight for their height. However, BMI alone is not an appropriate measure for children, because they are still growing. Factors such as rate of growth, age and sex, and the BMI of other children of the same age must be taken into account when assessing your child's weight. BMI is best interpreted with the help of your GP, health visitor, practice nurse or dietitian.

Maintaining a healthy weight

In most cases, experts recommend that overweight children should not be encouraged to actually lose weight. Instead they should be encouraged to maintain their weight, so that they gradually "grow into it" as they get taller.

Children should never be put on a weight loss diet without medical advice as this can affect their growth. Unregulated dieting - particularly in teenage girls - is thought to lead to the development of eating disorders. For more information, see the separate BUPA health factsheets, Anorexia nervosa and Bulimia nervosa.

There isn't much evidence for the best ways to treat weight problems in children, but research indicates that focusing on making long-term improvements to diet and increasing physical activity may be the effective solution.

Helping children to achieve and maintain a healthy weight involves a threefold approach that encourages them to:

• eat a healthy, well-balanced diet.

• make changes to eating habits.

• increase physical activity - in 2004 the Chief Medical Officer recommended at least 60 minutes of at least moderate physical activity a day for children

The good news is that it is probably easier to change a child's eating and exercise habits than it is to change an adult's.

A healthy well-balanced diet

If you are concerned about your child's weight, encourage a variety of fresh, nutritious foods in his or her diet.

• Starchy foods which are rich in complex carbohydrates are bulky, relative to the amount of calories they contain. This makes them both filling and nutritious. Sources such as bread, potatoes, pasta, rice and chapatti should provide half the energy in a child's diet.

• Instead of high-fat foods like chocolate, biscuits, cakes and crisps, try healthier alternatives such as fresh fruit, crusty bread or crackers.

• Try to grill or bake foods instead of frying. Burgers, fish fingers and sausages are just as tast y when grilled, but have a lower fat content. Oven chips are lower in fat than fried chips.

• Avoid fizzy drinks that are high in sugar. Substitute them with fresh juices diluted with water or sugar-free alternatives.

• Avoid fizzy drinks that are high in sugar. Substitute them with fresh juices diluted with water or sugar-free alternatives.

• Instead of sweets, offer dried fruit or tinned fruit in natural juice. Frozen yoghurt is an alternative to ice cream. Bagels are an alternative to doughnuts.

Changes to eating habits To achieve lasting effects, the whole family attitudes and habits towards food and exercise need to change.

• Try to set a good example with your own eating habits.

• Provide meals and snacks at regular times to prevent "grazing" throughout the day.

• Don't allow your children to eat while watching TV or doing homework.

• Make mealtimes an occasion by eating as a family group as often as possible.

• Encourage children to 'listen to their tummies' and eat when they are hungry rather than out of habit.

• Teach children to chew food more slowly and savour the food, as they will feel fuller more quickly and be less likely to overeat at mealtimes.

• Don't keep lots of high-fat, high-sugar snack foods in the house.

• Don't make outings for fast foods part of the weekly routine.

• Try to get your children involved in preparing food as this will make them more aware of what they are eating.

Physical activity

Doctors recommend a gradual increase in physical activity, such as brisk walking, to at least an hour a day.

• Encourage walking to places such as school and the shops, rather than always jumping in the car or bus.

• Suggest going to the park for a kick around with a football, or a game of rounders, cricket or frisbee.

• Visit a local leisure centre to investigate sports and team activities to get involved in.

• Make exercise into a treat by taking special trips to an adventure play park or an ice skating rink, for example. Involve the whole family in bike rides, swimming and in-line skating.

• When it is safe to do so, teach your child to ride a bike.

Reducing physical inactivity.

Physically inactive pastimes such as watching TV or playing computer games should be limited to around two hours a day or an average of 14 hours a week. Encourage children to be selective about what they watch and concentrate only on the programmes they really enjoy.

The emotional factors

Food can take on emotional significance when used to comfort or reward children.

• Don't use food to comfort your child - give attention, hugs and listen.

• Overnight. Avoid using food as a reward as this can reinforce the idea of food as a source of comfort. Instead of having a fast-food meal to celebrate a good school report, for example, buy a gift, go to the cinema, or have a friend to stay.