Damien Martin now calls himself "the most unlikely gym-bunny" but still remembers what a struggle it was to lose more than 100kg.
The 35-year-old manager from Manurewa almost halved his weight from 215kg to 113kg, losing an astonishing 102kg - a shade more than the weight of All Black Richard Kahui.
Mr Martin's mother Jean died in 2001 aged 48 from obesity-related illnesses but for several years his own efforts to lose weight were futile.
Four years ago, he decided "enough was enough".
"It was just a constant start-and-fail process," Mr Martin said.
But things changed when Mr Martin, who has a daughter, 10, and son, 8, joined a gym and completed a 12-week weight-loss challenge.
"That started the ball rolling, and I've just turned into the most unlikely gym-bunny."
Mr Martin said at his peak weight he gave no thought to what he was eating, and said the "Needn't" list [of foods which can be cut from your daily diet] would have helped him when he decided to start losing weight.
He had since realised about 75 per cent of losing weight is down to diet.
"Definitely the more you know about what you are eating, the better off you are.
"And I think when you are in that situation, the hardest thing is to get out of it. I mean, 49 foods, you've still got options, haven't you?
"It's not like saying eat lettuce and a carrot every day."
David Hill, a nutritionist at the Otahuhu Recreation and Youth Centre gym that runs the weight-loss challenges Mr Martin took up, also backed the "Needn't" list.
"There's lots and lots and lots of people out there who have very limited information about what is a healthy diet, or else it's just not registering with them.
"Food trumps exercise ... If [people who start an exercise programme] haven't corrected their diet the weight loss benefits of the exercise can get easily cancelled out," Mr Hill said.By Nicholas Jones Email Nicholas