A personal trainer who has rippling 6-pack abs because of a hidden medical condition says he’s proof that being lean doesn’t mean you’re healthy

• Personal trainer Ben Carpenter has a rippling six-pack but can't do a sit-up, he told Insider.
• Carpenter's ab definition comes down to his low body fat levels which are a result of chronic illness.
• He also engages his core muscles in exercises like pull-ups, bench presses, and squats.

Personal trainer and former fitness model Ben Carpenter has washboard abs, but never trains his core and can't do a sit-up, he told Insider.

The British trainer, who has built up a 178,000 strong Instagram following with his science-backed fitness posts, has a physique that most people would covet, including a six-pack.

However, this isn't the result of endless sit-ups or crunches, but rather his leanness.

"I don't train my abs," Carpenter told Insider. "I can't remember the last ab exercise I ever did."

If he lays on his back, Carpenter says he couldn't do a sit-up without assistance.

Carpenter has very low body fat levels due to Crohn's disease

Carpenter never trains his core specifically because he's never had to strive for more defined abs.

Spot-fat reduction - trying to lose fat in a particular body part - is impossible, so endless crunches or sit-ups wouldn't be much use to someone trying to get a flat stomach or a six-pack.

While the abs are muscles like any other which can be built up, most people need to eat in a calorie deficit to lose body fat around their mid-section to reveal their abs underneath.

Carpenter suffers from irritable bowel disease and Crohn's, which means he has always been lean - and on two prolonged occasions during his early 20s, unhealthily so.

He says his lack of core training comes down to "laziness."

"For a long time, probably because of Crohn's disease, I've had a body fat level so low that everyone has assumed I train my core," Carpenter said. "Because of that, I've just never bothered."

He said he struggles to put on weight because of stomach issues.

"Because I have been genetically blessed/cursed with inflammatory bowel disease, by most stereotypical cultural standards, I've always had aesthetically pleasing abs. So I just don't do anything," Carpenter said.

Carpenter engages his core in other exercises

When training, Carpenter is motivated by trying to increase his strength on movements like the bench press or squats, but has never gone into a workout feeling like he wants to improve his abs.

"Doing things like pull-ups with an additional 70kg (150 lbs), there is definitely core engagement there and an isometric hold position," he said. "But an actual sit-up with full hip-flection, I can't do it."

Carpenter said many people see his physique and want to know his fat loss advice, but he wants people to know that leanness does not equal health. He's releasing a book in 2022 to give fans an inside look at his journey.

"There's an automatic assumption that I am healthy, happy, and fit based on how I look, but I'm not that fit," he said.

Carpenter recalls times in his life when he was dieting severely for photoshoots, was "malnourished," would get out of breath walking up the stairs, and pull a hamstring bending to tie his shoelace.

"But the photo would look good for social media," he said.