A man who once weighed close to 275 kilos (600 pounds) has achieved a sensational milestone by losing more than half his body weight after a threat of death.

Adam Slack, 37, of New Jersey has lost 170 kilos since 2008 when a doctor asked him to write his own obituary, ABC local has reported.

The married father of four reportedly weighed 265 kilos then, suffered from high blood pressure, type 2 diabetes and could not even get through completing routine tasks.

His wife, Michelle, tells Good Morning America she used “to tie his shoes and help him put on his pants”.

It was in the June of 2008 that the unhealthy lifestyle caught up with Slack and he nearly passed out during his shift as a security guard at an Atlantic City casino.

He was rushed to the emergency room of a nearby hospital and it was there that his phenomenal journey to weight loss began.

“A doctor walked into my room and the first words out of his mouth were, ‘Uh, hello Mr. Slack, what would you like in your obituary?’” Slack was quoted as saying, “I yelled at him and told him to leave the room. It was the darkest place, but it was also a rebirth.”

Slack then began a journey into a new, healthy life and began exercising in his neighborhood. He also visited AtlantiCare Lifecenter three times a week to help speed up his weight loss.

“He looks great and a big difference. It’s a transformation and he looks healthy,” Dr Ireno Bustmante of Atlantic Emergency Associates was quoted by ABC as saying.

Slack now coaches his son’s baseball league.