A greasy Chinese take-away washed down with treacle tart and clotted cream is a recipe for days of guilt-induced fasting and sit-ups for most of us.

But for John Perry, 59, his days of counting pounds are over and after deciding to donate his unusual body to science, he is hoping to give us all a ticket to eat our hearts out.

At the age of 12 Mr Perry went from being the chubby kid in the playground to a "bag of bones" almost overnight, after developing a rare condition known as total body lipodystrophy which stops him putting on weight.

While most people struggling to shed pounds would give their right bingo-wing to develop Mr Perry's condition, he said he would regularly scoff chocolate as a youngster to try and bulk out his skinny frame.

Mr Perry now eats a fairly balanced diet, but enjoys the fact that he can happily tuck in to unlimited burgers, take-aways and fatty desserts while his 11st 12lb frame stays rock steady.

At first doctors thought he had a stomach ulcer, and Mr Perry endured decades of hospital visits and tests before he was finally diagnosed with the condition that sees his body produce six times the normal amount of insulin.

Now Mr Perry, who has quickly become the talk of the town and the country after appearing on TV and in the national press, hopes he can help solve Britain's obesity problems by offering pharmaceutical companies the chance to find his fat defying hormone.

He said: "For the last year you can hardly pick up a newspaper without reading something about obesity.

"It occurred to me that I might have the answer to it."

Mr Perry, of De Vere Gardens in Ilford, added: "I'm used to the intrusion as I was told I was the most tested person ever at the Royal London Hospital and I was presented to the Royal Society of Medicine where I had about 40 doctors poking and prodding me.

"If they can pin-point my hormone then dieting and obesity will be a thing of the past.

"The implications are mind-boggling."