Many overweight people have tried and failed to lose their excess pounds, often on many occasions. One author reckons that weight loss will only be successful when the obese person has undergone an “epiphany”; a moment when they realise just how much their extra weight is affecting their health or social life.

“I think one of the reasons many of the [weight-loss] programs are abandoned is that the pain isn’t painful enough,” said Timothy Ferriss, author of “The 4-Hour Body.”

Celebrity simmer and Subway spokesperson Jared Fogle agrees that you need something to get you motivated and to keep you committed when trying to lose weight.

“When you’re in public scrutiny like that, it’s never easy,” he said. “You look at someone like Oprah Winfrey and she’s always dealt with that. At the same time, it’s giving me more motivation to definitely keep the weight off.”

For one Boston man, the defining moment came when a friend from Australia was visiting and they tried to go out for dinner with some friends.

37-year-old Matt Hoover, who at his heaviest weighed nearly 500 pounds, and suffered an embarrassing moment when the group arrived at the local restaurant.

“I couldn’t fit into the chair they had there,” Hoover said. “It was really embarrassing — just a horrible scene. They had chairs with arms. You had to be a certain width.”

Hoover had to leave the group to enjoy their dinner and arranged to meet them at a nearby coffee shop after they had finished. “My size was preventing me from doing things that other people took for granted,” he added.

After seeing a photo of himself that a friend posted online and realising how big he actually looked, Hoover decided enough was enough. He now weighs just 185 pounds and is even in training to run half marathons.