They also want school meals to be subjected to strict guidelines on sugar and fat content, as well as minimum levels of vitamins and minerals.
The recommendations were published by the British Medical Association (BMA) in a major report, 'Preventing Childhood Obesity', launched yesterday.
The BMA, which represents around 130,000 doctors, or about three quarters of those practicing in the UK, says that there are around 1 million obese children under 16 years of age in the UK. If current trends continue, at least one fifth of boys and one third of girls will be obese by 2020.
The soaring rates in obesity have led to an increase in childhood type 2 diabetes and will lead to more future cases of heart disease, osteoarthritis and some cancers, according to the report.
Dr Vivienne Nathanson, head of the BMA's science and ethics group, said: "Children are being bombarded with mixed messages. On one hand they might learn about healthy eating at school and then they go home and spend hours watching TV and see celebrities eating hamburgers, crisps or drinking fizzy drinks. Children and parents are surrounded by the marketing of unhealthy cereals, snacks and processed meals - this has to stop."
Worldwide over 22 million children under five are severely overweight. Experts say junk food and low exercise levels, combined with the popularity of computer games and television, are behind the growing obesity rates.
The new report laid much of the responsibility for tackling the epidemic with the government, calling on it to mount a sustained public education campaign to improve parents' and children's understanding of the benefits of healthy living, and also subsidise the cost of fruit and vegetables to encourage healthy eating.
However it also requested that manufacturers be legally obliged to reduce salt, sugar and fat in pre-prepared meals to an agreed level within a defined time frame, and that celebrity endorsement be restricted to products that meet nutritional criteria laid down by the Foods Standards Agency.
Although there is no precise figure of how much obesity costs the country's national health service (NHS), every year it spends at least £2 billion on treating ill health caused by poor diet. Costs are likely to increase unless measures are put in place to halt this growing problem.
Childhood obesity has become a major political issue in Britain partly due to a successful campaign by 'Naked Chef' Jamie Oliver who revealed the poor quality of food being served to children in state-run schools.
Yesterday, another celebrity chef, Gordon Ramsay, teamed up with the Food Standards Agency's Focus on Food campaign running this week to highlight the importance of food education in schools. Ramsay will visit schools to give children tips on how to cook.
It is estimated that about 10 percent of children or at least 155 million youngsters worldwide are overweight or obese.