Usain Bolt has no regrets over his decision to retire later this year but vowed to stay in shape after ending his phenomenal athletics career to avoid losing a bet for growing a "belly".

Eight-time Olympic gold medallist Bolt will race for the last time at the World Championships in London in August.

The legendary Jamaican sprinter will go down as a sporting great regardless of whether he signs off in style on the track at the venue that hosted the 2012 Olympics.

Bolt, 30, said there is no chance that he will change his mind and perform a U-turn.

"Everybody wants me to continue but it's not as simple as it is, you know what I mean? For me, I've done what I wanted to do. I've done great in the sport," he told BBC Sport.

"People just want to see more and more but you as a person have to decide that this is it. I don't want to continue and then at the end I start losing, because I hate losing.

"No regrets. If you look at a lot of top athletes, that's the one thing they use to damage their career just a little bit.

"By being so dominant through their career, retire, then miss the sport and then come back in to something different. I don't think my coach would coach me either.

"I have a bet with my managers. They give me two years before I get at a belly, so I can't let that happen!"