(CNN) He sprinted his way to fame at the 2008 Beijing Olympics, winning three gold medals and setting a trio of world records -- and all powered by a diet of fast food.

Usain Bolt's love of junk food -- especially chicken nuggets -- has been well documented, but now at the age of 28, the Jamaican is ready to change the way he refuels.

"Food wise, I have to eat a lot more vegetables," he explained to CNN's Amanda Davies, almost sounding like a boy being told by his mother to finish his greens.

"I have to cut junk food out. I think that's one of the biggest things for me, because I get a lot of urges at late nights, just to eat junk food. For me, that personally is one of the biggest sacrifices."

And it really is a sacrifice given Bolt estimates in his autobiography "Faster than Lightning," that he had devoured 1,000 McDonald's chicken nuggets during his 10 days in Beijing -- a whopping 5000 calories and 300 grams of fat a day, all because he found Chinese food "odd."

Vegetables may be a new addition on the Bolt menu, but don't expect him to be cooking them.

"I can't cook, that's the one thing I can't do, though I can make scrambled eggs," he confessed ahead of the Anniversary Games in London.

Team Bolt we remain strong and we continue to work hard towards the goal at hand.. Thanks all the love and support my peeps and keep believing anything is possible..No Limits #ForeverFaster A photo posted by Usain St.Leo Bolt (@usainbolt) on Jul 24, 2015 at 3:21pm PDT

But if you ever feel guilty about breaking a diet, you shouldn't, as even the world's greatest athletes are still prone to the odd slip-up.

"Sometimes you do think about just going out or just not training, or just eating a million hot wings. It's hard sometimes, because you crave it, because you're used to doing a certain thing.

"It's hard to just walk away and not slip up sometimes. So it happens, but I try to not make it happen on the regular. I try to just contain myself as much as possible."

As well as resisting deep-fried chicken temptations, Bolt has also become more conscious of his body clock and whether that is helping or hindering his athletic performance.

"Oh, I think it's just not sleeping [is my biggest weakness.] I'm so used to staying up at night, especially playing video games or just watching movies.

"I think that's one of my hardest things to overcome, trying to go to bed early. Even when I want to sleep, I tend to try to fight the sleep and not go to bed."

It would appear Bolt's new healthy diet and early bedtimes are starting to pay off, as he recorded his fastest time of the season -- 9.87 seconds -- at the Anniversary Games to take the gold medal in the 100m on the same track he tasted Olympic glory on at London 2012.

100m final 1st @usainbolt 9.87, 2nd Rodgers 9.90, 3rd Bailey-Cole 9.92 #AnniversaryGames — British Athletics (@BritAthletics) July 24, 2015

The British capital has been the backdrop to some of the greatest moments in Bolt's career and it will set the scene for his curtain call.

The date of Bolt's retirement has been set for after the 2017 World Championships for some time and, by the sound of it, the world's fastest man will unlikely be tempted to postpone.

"Yes, that'll be it for me. I think there's nothing else for me to either accomplish after those next two seasons. So why stay in the game?"

Despite his impending retirement and inability to resist unhealthy food, Bolt is confident his waistline won't be expanding in the future.

"Hell no [I won't get fat]," he said, chuckling at the thought. "That's one thing I'm determined not to have. I have a bet with a couple of people.

"I have a bet with Ricky Sims (Bolt's agent,) I have a bet with my coach (Glen Mills.) I have a bet with a few people because everybody says I'm really lazy, so in like two years after I retire I'm going to have a big gut.

The Winning Team #CoachMills #Guru #ForeverFaster A photo posted by Usain St.Leo Bolt (@usainbolt) on Jun 12, 2015 at 12:27pm PDT

"I have to take up something, I don't know what I'll have to take up. But for sure I'll be doing something. Just not running."

Bolt's last hurrah at the Olympics will come at Rio 2016 and, with just under a year to go, it is very much on his mind.

"I think the closer it [Rio] gets, I think about it way more," the six-time Olympic gold medallist said.

"Initially, it wasn't that much, I didn't think about it. But now it's really been on my mind. I think it's because it really means so much to me, I really want to go to Rio and do so well.

"I've even talked to my friends already. I said: 'Listen to me, you guys got to keep me focused next season, make sure I stay on top of things.' So I've already tried to start putting things in place.

"But I really think about it a lot. I just tell my friends because I know sometimes I'll just be up and I was like: 'Yo, let's go hang out.'

"I tell them: 'Listen to me, say no sometimes. Say no, let's not hang out today.'

Above all, though, it's the prospect of not letting down his coach Glen Mills that keeps Bolt on the straight and narrow.

"My coach most of all. He really stays on top of things, and he knows me very well," he said.

"I think just looking at me he can tell when I have done something wrong. I feel sometimes he's bluffing, but when you're guilty, it plays on your conscience.

"But he knows well because I show up at training sometimes and he goes: 'You went out last night, didn't you?' And I go: 'No.'

"But I can tell he knows what's going on."

The Jamaican is known for his on-track showmanship and love and enjoyment for what he does. However, from now until Rio, we'll be seeing an altogether more serious Bolt.

.@usainbolt talks to CNN ahead of tomorrow's Sainsbury's Anniversary Games at the Olympic Park in London. pic.twitter.com/PoT1fb5aUe — CNN Sport (@cnnsport) July 23, 2015

"It's going to be all work next season. I think there's going to be zero fun next season for me," he said with a serious tone.

"That season is very important to do the Olympics back-to-back. For me, that's the biggest thing in my career. So I know what it will take and I know what I have to do.

"So next season, strictly work."

Bolt's "Double-Triple" -- gold medals in the 100m, 200m and 4x100m relay in Beijing and London -- is an historic feat in itself, but the Jamaican is supremely confident of recording an unprecedented "Triple-Triple."

Just how sure is he of writing a new page in the history books?

"A hundred percent. As long as I'm fit, I have no doubt.

"I know my capability, I know what it takes and that's the key thing.

"That's what I always explain to people."

Before he does bid his farewell to athletics, Bolt is equally confident he will set his own bar even higher and continue to break records.

"Yes, without a doubt [I can break them.] I think -- and I've said it every year -- if I just could get a season where I just go through with no problems, then I know that I'll be breaking world records easy.

"So for me, I think next season I'll go to my doctor more, get more check-ups, be aware just of everything around me and my surroundings and just things that I need to do to stay in shape.

"I think I'll be much more aware of these things because I need to be at the best when I go to Rio, at my absolute best.

"I don't want what happened this season to happen next season, people doubting me that if I'm going to do great, if Usain's going to win.

"I don't want that at any point in the season, so I'm going to make sure I stay on top of my game."