Winning a £25,000 prize presented to him by Davina McCall, the Ayrshire-born 29-year-old shed a total of 8st 7lb since the series started nearly two months ago.
Reflecting on the victory today, he told The Mirror: "I'll be 30 this month and I'm really looking forward to it. I feel like I've lost my 20s, I let my weight hold me back.
"I didn't have a girlfriend in my 20s. If someone showed any interest I'd think they were taking the Mick or doing it for a bet. If I didn't like myself, how could anyone else? I've been on a few dates. I haven't found the right person yet, but I've got hope now."
Meanwhile, Graham also revealed how he would spend his winnings: "We have never had the money. My mum and dad have always worked really hard for the family, so I can't wait to take them away.
"I am going to let them choose the destination. They fancy Greece or Turkey but I have told them to look a bit further afield because we can afford it."
He added: "I would not have even been able to stand up and watch someone do a triathlon. My whole attitude has changed and I am really lucky I got the chance to appear on the Biggest Loser. I didn't have a life before - Biggest Loser has given me one."
The Biggest Loser, which has aired on Monday nights, has piled on viewers, and last night hit a series high of 4.7m.