Bookie William Hill has conceded that warehouse worker Ian Armstrong, 44, has hit the target he set in January by getting from 17st 5lbs to 12st 5lbs by his festive deadline.

The bookmaker said it is its record weight loss for a bet of this type.

A spokesman for the firm said it takes hundreds of bets on predicted weight loss like Mr Armstrong's every year but it hardly has to pay out.

Now Mr Armstrong is ploughing his winnings into the boys football team he chairs in Bradford, West Yorkshire - the East Bowling All-Stars.

Mr Armstrong, who works at the Morrisons depot in Wakefield, said he piled on the pounds after he got a knee injury while out running.

But he decided to diet his way back to fitness as a way of raising cash for the All-Stars, and after a little encouragement from his wife, Tracy. He said his sons Nathan, 10, and Niall, seven, have also been very supportive. They both play for the All-Stars teams.

"It's incredible when you look at the pictures of me before and what I'm like now," Mr Armstrong said. "It's a huge amount to lose but I feel so much better."

He said he managed his dramatic weight loss by changing his diet. And his top tip is to drink a pint of water before meals to cut down your appetite.

"I haven't been following anything in particular. I've just done it myself. It's amazing how everything changes when you ditch the big portions of pie and chips and go on to the rice pasta chicken instead. The charity shops have done well out of it, though. I've had to buy a whole new wardrobe."