Ref. 74435-22FAT lads John Donaldson and Tony Scull weight a total of 78 stone which is just under half a tonne.
Now they are hoping to give charity funds and themselves a healthy boost by shedding weight.
And to launch the bid, the pair's weigh-in had to take place on a weighing bridge at Saunders scrap merchants in Barnfield Road, Swindon, because of their size.
The men have a larger than life presence at their regular drinking haunts, The Tap and Barrell and The Wheat-sheaf in Swindon.
Both pubs put them up for the challenge and are supporting their sponsorship drives. Cash raised will be donated to Prospect Hospice in Wroughton.
Doctors told John of Greenmeadow, that unless he lost weight he would be dead by the time he was 35, but now aged 44, the greasy-breakfast lover has defied all predictions.
The former Commonweal School pupil is now 37 stone and has a special reason to raise cash for Prospect, as his cousin Shaun Jennings, 26, and father-in-law, Bob Dodgson, received care at the hospice until they died.
And as well as losing weight for charity, he is determined to shed the pounds so he can squeeze into a proper suit before marrying Jenny Doyle, 47, in December.
Despite associated health problems, John, who owns BJ's Furniture Store in Gorse Hill and has two children, Leslie, 23, and James, 20, is good-humoured about his size.
"Swindon Council has banned me from jogging because I was breaking all the paving slabs," he quipped.
"But seriously, I plan to lose weight by cutting out alcohol and daily fried breakfasts and by doing gentle exercise like swimming."
Staff at the Tap and Barrel in Manchester Road, which is also collecting for the Tsunami Appeal, have agreed not to serve Mr Donaldson any beer to help the weight fall off.
Landlord Tom Fitzgerald, 44, said: "I think they both need to lose the weight.
"And it's good they are doing it for charity."
Father-of-two Tony, who is 41 and a half stone, said he has taken inspiration from former darts world champion Andy Fordham, who has signed up for ITV's Celebrity Fit Club.
The 30-year-old, of Haw-thorn Avenue, Pinehurst, said he wants to reach his target by cutting out beer and fizzy drinks.
"I just want to feel more healthy," he said. "What's good for charity is good for me."
John Bristow, manager of the Wheatsheaf in Dores Road, who is supporting his bid, said: "I think it's a great way to lose weight."
The challenge will end in early July to coincide with The Tap and Barrel's charity fun days.
To make a pledge, phone 01793 723246 or 01793 432587.
Ben Payne
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