Britain is in the grip of an obesity epidemic costing £5bn a year - and not enough is being done to tackle it, according to the Royal College of Physicians.
A report by the RCP says severely overweight patients are suffering from what it calls "patchy" NHS services and a lack of joined-up thinking from the Government.
Thirty-one-year-old Matthew Briggs, from Strensall, near York, says the NHS was of little help when he weighed more than 31 stone.
Now more than 17 stone lighter, and Slimming World's 2012 champion , he says he was offered slimming pills and a drastic diet.
"They gave me very limited options of what I could have," he said.
"You only see your GP for 15 or 20 minutes (and) you've got an entire week or month before you see them again."
He says he eventually relied on a combination of willpower and encouragement from other overweight people to help him slim down so much he is now training for the London Marathon.
The RCP report calls for teams of specialists to be set up around the country along with a national anti-obesity group similar to Action on Smoking and Health , which is credited with helping to reduce the number of people who smoke.
The authors also want to see an obesity champion in each NHS trust, better training for health care professionals, more research into obesity and help for overweight NHS staff.
With around a quarter of UK adults classed as obese, the report says too many doctors and nurses are seriously overweight and setting a bad example to the people they are trying to treat.
Professor John Wass, academic vice-president of the RCP, said: "Britain is getting bigger and whilst we try to prevent the increase in obesity, we must also prepare the NHS for the influx of patients presenting with severe complex obesity."
A Department of Health spokeswoman said: "We are committed to tackling obesity and are taking action to help people keep a healthy weight and prevent them needing hospital care for obesity-related conditions.
"The medical profession has a key role in providing advice and treatment to people who are overweight or obese, and the Royal College of Physicians can help its members do this."