At on-set the children get a medical examination, blood-tests, measurement of height, weight, skin-fold, waist and hip. Children and parents fill out questionnaires on social and educational background as well as motivation and expectations to the treatment. All Children are thereafter randomised into two groups:multi-disciplinary group intervention versus traditional information. The randomisation is stratified according to gender and degree of overweight (135%-145% and >145%) supposing that the degree of overweight may mirror the difficulties in loosing weight. The experimental intervention consists of one lecture of general nutrition, weekly psychological group sessions for the children followed by physical exercise, and separate bi-monthly group sessions for the parents. After six months children and parents go to separate group sessions once a month for six months. The control group is offered nutritional advice once with a brief follow-up after one month. The height and weight of the children is measured every month, and the fat % is measured with DEXA-scanning at on-set, after six months, and after twelve months