The world's heaviest man is hoping to lose a staggering 68 stone to become the globe's greatest slimmer.

Manuel Uribe is dieting while confined to a reinforced bed that he has been unable to leave for the past six years.

He has lost 37 stone since March 2006 on a diet of grapefruits, egg-white only omelets, fish, chicken, vegetables and peanuts.

The 42-year-old - who now weighs more than 51 stone - said Guinness have spoken to him about his diet.

US woman Rosalie Bradford, who died in 2006, held the record for losing the most weight, shedding 52.5 stone in the early 1990s, according to reports.

Mr Uribe said his goal is to weigh 20 stone by 2010, meaning he would have lost 68 stone.

The Evangelical Christian, who used to weigh more than half a tonne, spent the 1990s guzzling pizzas, burgers and fizzy drinks in the US, working as a computer repairman.

Addicted to junk food, he eventually bulged to more than 88 stone back in Mexico, binging on greasy tacos.

That made him the world's heaviest man and won him a place in the 2008 edition of the Guinness World Records. It is not clear if his dramatic weight loss means someone else will take the title next year.

Abandoned by his wife, his health failing and with no income, Mr Uribe despaired and pleaded for help on Mexican television, stirring up international interest.

Cared for by his mother Otilia, Mr Uribe turned down offers of gastric bypass surgery in Italy. Instead he took free medical help from US doctor Barry Sears, choosing to follow the Zone Diet, which is high in protein and low in carbohydrates.

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