If you've ever attempted to eat an 18-inch pizza in one sitting you'll know how much it hurts.

Once the initial 'mmmm delicious pizza' phase subsides after a few slices, that's when cheese sweats and the stomach cramps set in. Then it's just pure stuffed-crust misery all the way from there. If you do managed to plough your way through the whole thing, you're left curled up in the foetal position for the next few days nursing a monstrous food baby. It certainly does do your physique any good. That's what makes it all the more incredible to see professional eating champion Takeru Kobayashi rocking one of the most impressive six packs we've ever seen. He is the ultimate competitive eater. There is nothing this dude cannot polish off. He holds eight Guinness World Records for eating anything from ice cream and tacos to hot dogs and pasta. He ate 62 slices of pizza in just 12 minutes at the 'Let Em Eat' contest in Canada in 2014 - which equates to 15 and a half whole pizzas. But the craziest part is that the 38-year-old doesn't even weigh 10 stone and he's absolutely shredded. So how do you eat more than 6,000 calories in one sitting and still manage to have abs? What witchcraft is this? First of all his technique is to expand his stomach leading up to competitions by eating larger and larger volumes of food - and even uses water in place of food to increase his stomach's capacity. However to stop body fat building up, which impedes the expansion of his stomach when he's eating 100 hot dogs, he exercises like an absolute beast. Weight training and high intensity cardio are too ways to keep your metabolism high and burning off calories quickly. Kobayashi trains three times a week using a heavy weightlifting programme which can increase your metabolic rate for up to 48 hours after. Interestingly this is where his impressive six pack comes from rather than doing thousands of sit-ups every day. "The truth is that I've never done a sit-up in my life, he told Weight Watchers through his translator Maggie James. "You will eventually get that stomach from lifting weights. I love lifting. That's always where I'm more focused." Exercises like heavy squats and deadlifts are an incredible core workout and something that he has used to shape his abs. His incredible physical condition primarily comes from weightlifting - but he does some running and when he's not competing he tried to eat three small and balanced meals a day. He favours lean proteins and lots of green veg, as well as yoghurt and tofu. But leading up to a competition he scales back his workouts to focus on competition-specific eating - whether it's pies or pizzas - but still keeps his protein levels high to preserve his hard-earned muscle tissue. He will cut his weight down to around 132lbs (59kg) which is his ideal competition weight with less than 10% body fat. Another obvious reason Kobayashi stays so lean is that he appears to be a classic ectomorph. While most of us will probably stick 10lbs on just looking at a carb, ectomorphs have a ludicrously high metabolism. https://www.youtube.com/watch?v=fodNp6zup_E So anything they eat they can burn off pretty quickly. That's why so-called hard-gainers have to eat thousands more calories just to put any size on. While Kobayashi is clearly a phenomenon and a  freak of nature, it's not impossible for mere mortals to enjoy stuffing their faces on the odd occasion while still keeping their abs. Leeds professional eater Adam Moran is a prime example. He does 10,000-calorie eating challenges on his YouTube channel every week. His trick is to eat all his daily calories in one meal, fasting the rest of the time. His food is clean, healthy and balanced for the whole week - until his eating challenge, obviously. But he says this massive dump of junk food helps to boost his fat-burning hormones and restore his glycogen stores after a hard week weight training.