A MAN who used to weigh 42 stone and was so large he could barely walk has spoken of his “rollercoaster” experience after undergoing a life-saving operation.

Greg Simpson, 33, of Turners Close in Ongar, was told by doctors he would not live to 30 unless he had a gastric bypass to dramatically reduce his size.

Faced with the prospect of leaving his two young children without a father, Mr Simpson agreed to the procedure and has now lost an incredible 24 stone, thanks to the surgery and extensive workouts at a gym.

But despite his remarkable turn-around, Mr Simpson said he wanted to warn others about the perils of weight-loss operations.

“A gastric bypass is often made out as a quick-fix, but it isn't. What they don't tell you is about all the side effects and negatives,” he said.

“Since the surgery my body hasn't been able to deal with food or drink. Most babies eat more than me.

“You get a lot of excess skin which is absolutely disgusting, and it is a real shock how different you become.”

Mr Simpson, who works as a traffic officer, said he first started to put on weight during a growth spurt as a teenager.

After being “horrifically” bullied by his peers at King Harold School in Waltham Abbey, he found solace in playing American Football and travelled around the world representing Britain at various international championships.

But despite getting married and witnessing the birth of his two children, Mr Simpson continued to put on weight, until doctors urged him to take action or face death. The ordeal also prompted the break-down of his marriage.

But now happily in a new relationship, job and hobby – as a strongman competitor – Mr Simpson is looking to the future.

He said: “It's been an absolute rollercoaster. My advice to other people in the same kind of situation is that you should try everything else to lose weight before having a gastric bypass. It should only ever be a last resort.

“But at least now I can play with my kids and not feel exhausted after a few minutes. I feel I can just get on with my life.”