|Astrologer Russell Grant has been warned he could drop dead at any minute if he does not lose weight.
The Celebrity Fit Club contestant weighs a whopping 22 stones.
And he was left reeling when the ITV show's nutritionist Dr Adam Carey told him it was amazing he was still alive.
"My stars for this weekend told me to prepare for a shock, but I had no idea," said 54-year-old Grant. "First I was told I weigh nearly 22 stones, which for someone of my tiny height sent me reeling.
"Then Dr Adam looked at me very seriously and said he had programmed in all my various health problems from heart to weight and the result was I should be dead already."
He admitted: "It has hit me like Hurricane Katrina. Not only am I close to death if I don't do something radical with my weight and health, but I am literally hanging on by my fingertips as I should already be dead."
Dr Carey said: "He is the sickest person we have had on Celebrity Fit Club by a long way."
Viewers will see Grant attempt to lose weight in the new series of Celebrity Fit Club, which begins on Monday night. Eight celebrities will be put through their paces by US drill instructor Harvey Walden.
The other contestants are broadcaster Anne Diamond, This Morning TV expert Sharon Marshall, darts player Bobby George, actor Jeff Rudom, football legend Mick Quinn, former Hollyoaks actress Mikyla Dodd and journalist Carole Malone.
Diamond, who once released an exercise and diet DVD, weighed in at 14 stone 9lbs and was found to be morbidly obese with 44% body fat. The former breakfast TV star admitted she had not stood on the scales for a long time and was "terrified" about discovering her true weight.