Spencer Matthews has dropped 26lbs ahead of his charity boxing match with Wayne Bridge for Sport Relief.
The former "Made in Chelsea" star will enter the ring with the retired footballer - who is married to The Saturdays" Frankie Bridge - and has shed the pounds so he's the correct weight to fight, which he's hoping will be worth the effort.
He revealed to OK! magazine: "I've lost 26lbs which is 12kilos in order to make the weight.
"I was a bit porky before don't get me wrong, but it's been a pleasurable journey for me to just get really back into full on health and fitness and opportunity to pick up a new sport.
"I'm pretty used to taking punches now.
"There's boxing to keep fit and there's training to fight, and this is training to fight.
"I knew it would be difficult and I knew in order to get the win we would have too put in the time.
"I hope the amount of effort we put in reflects on the night."
Spencer and Wayne - who previously played for the likes of Chelsea, West Ham and Manchester City during his career - will pick up for their boxing gloves on March 23 for Sport Relief, which will be aired on BBC One.
The 29-year-old ex-loathrio - who is engaged to presenter Vogue Williams - has been left "completely drained" after hitting the gym relentlessly.
He admitted: "On the rest days you're beginning to fall asleep in cabs.
"Your body is just completely drained."
However, he is delighted to help the charity event by Comic Relief and BBC Sport, which brings together the worlds of sport and entertainment to raise money to help vulnerable people in both the UK and the world's poorest countries.
He said: "I've always wanted to do something with Sport Relief and they just do so much good around the UK and others ares of the world."
Six fearless celebrities will don their gloves and take to the ring in a series of bouts next week.
"EastEnders" star Hannah Spearritt goes head-to-head with The Saturdays" Vanessa White, and "Love Islands" Camilla Thurlow takes on presenter Helen Skelton.