London: Usain Bolt's managers have joked that he will develop "a belly" within two years of retirement, but he says that he has no doubts about hanging up his running spikes.

Bolt, 30, will retire after the World Championships in London in August after a sensational career in which he has amassed eight Olympic gold medals, 11 world titles and three world records.

"Everybody wants me to continue, but it's not as simple as it is. I've done what I wanted to do. I've done great in the sport," Bolt told the BBC in a television interview to be broadcast on Saturday.

"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 start losing, because I hate losing.

"There are no regrets. You look at a lot of top athletes; they used to damage their career just a little bit. By being so dominant through their career, [they] retired, then missed the sport and then come back into the sport for something different. I don't think my coach would coach me either."

Though famously fond of the high life, Bolt says he does not intend to lose control of his waistline once he stops competing.

"I have a bet with my managers. They've given me two years before I get a belly," he said with a chuckle.

"I can't let that happen."

With eight Olympic titles, 11 World Championship gold medals and three world records, Bolt has been the most dominant athlete on the planet since he first burst on the scene at Beijing 2008.

Despite winning three Olympic gold medals in Rio, Bolt has been stripped of his status as the 'triple-triple' champion after losing the gold medal won in the 4x100m relay due to Nesta Carter testing positive for a banned substance.

Though an appeal been lodged over the ruling, Bolt may have to retire with just the eight Olympic gold medals.

Bolt is expected to compete in the 100m, 200m and 4x100m for the final time at the Olympic Stadium, where he won his first Olympic treble at London 2012.

Meanwhile, the radical plan to wipe out athletics' world records set before 2005 was not a cowardly proposal, a senior member of the sport's governing body said on Thursday.

Olivier Gers was responding to criticism from Britain's Paula Radcliffe, the women's marathon world record holder, who stands to lose her place in the record books if the root-and- branch idea goes ahead.

"I am not sure what's cowardly about this," said Gers, chief executive of the IAAF said.

"It's a sad reality of our sport that we are doubting some records.

"What it allows us is to reset the bar. It's a very difficult decision."

Gers also said that mixed-gender relays are being considered as an Olympic event to ramp up interest in athletics.

"As a sport we are looking at different formats. It's definitely something for the Olympics to look at and for the IOC to decide jointly with the IAAF.

"It's definitely something we have been talking about for quite some time."

Mixed-gender relays saw a trial run at the IAAF World Relays in Nassau in April. A 4x400m event, with two men and two women per team running in no set order, proved a highlight at the championships in the Bahamas, especially as the home team won.