A campaign group has called on the Government to introduce a "sugar tax" to discourage consumption of sweetened soft drinks.
Action on Sugar said it had developed a seven-point plan to curb childhood obesity following a request for its views from Health Secretary Jeremy Hunt.
The measures include bringing in a sugar tax, limiting the availability of ultra-processed foods and sweetened soft drinks, and banning "junk food sports sponsorships".
The group's chairman, Professor Graham MacGregor, said: "Obesity in children leads to the premature development of cardiovascular disease, stroke, heart attacks and heart failure, which are the commonest cause of death and disability in the UK.
"Obesity predisposes to type II diabetes, which further increases the risk of cardiovascular disease and also, importantly, it can lead to severe complications, i.e. the commonest cause of blindness, renal dialysis and amputation of the lower limbs.
"These complications are extremely expensive to manage, and will cripple the NHS if the increase in obesity and type II diabetes is not stopped immediately.
"Obesity is preventable if the food environment is changed, yet the current policies are not working. The UK requires the implementation of this coherent strategy, starting by setting incremental sugar reduction targets for soft drinks this summer. No delays, no excuses."
Dr Aseem Malhotra, cardiologist and science director of Action on Sugar, said: "It is really quite shameful that the food industry continues to spend billions in junk food advertising targeting children, the most vulnerable members of society. They even manage to associate sugary products with sport.
"Physical activity has a multitude of benefits but a child doing an hour of PE every day would be putting all to waste if they ended up gorging on a burger and chips and a packet of crisps washed down with a sugary drink. One has to run half a marathon to burn off those calories. It's time to bust the myth of physical activity and obesity and dissociate junk food and sport."
The seven measures called for are:
:: Reduce added sugars by 40% by 2020 by reformulating food
:: Cease all forms of targeted marketing of ultra-processed, unhealthy foods and drinks to children
:: Disassociate physical activity with obesity via banning junk food sports sponsorships
:: Reduce fat in ultra-processed foods, particularly saturated fat - 15% reduction by 2020
:: Limit the availability of ultra-processed foods and sweetened soft drinks as well as reducing portion size
:: Incentivise healthier food and discourage drinking of soft drinks by introducing a sugar tax
:: Remove responsibility for nutrition from the Department of Health and return it back to an independent agency
Action on Sugar is a group of specialists concerned with sugar and its effects on health, which is working to reach a consensus with the food industry and Government over the harmful effects of a high sugar diet, and bring about a reduction in the amount of sugar in processed foods.
A Department of Health spokesman said: "We know some people eat too many calories including sugar. Childhood obesity is at its lowest since 1998 but more should be done.
"Next week we will get expert scientific advice on sugar which will help shape future thinking. We will consider these recommendations as part of this."