Most fitness challenges are built around balance.
Train everything. Hit your weak points. Don’t skip leg day.
But one YouTuber decided to throw that entire idea out the window and test something far stranger — what if you trained just half your body and ignored the rest?
Not upper body and lower body.
Literally one side.
That’s exactly what creator James Chewbonic set out to do in a bizarre 100-day experiment that left viewers wondering whether he’d end up with a subtle strength advantage… or looking like a real-life fiddler crab.
James, who admitted he’d “never been much of a gym goer before,” wanted to find out what would happen if he committed to only training the left side of his body for more than three months.
It sounds simple in theory, but the logistics were anything but.
To make it work, he had to strip his workouts right back and build them around unilateral movements — exercises that isolate one side at a time.
That meant things like bicep curls, pistol squats, dumbbell chest presses and side planks became the foundation of his training.
Every rep. Every set. Left side only.
The right side? Completely untouched.
At least that was the plan.
And because apparently the gym challenge alone wasn’t chaotic enough, James also took things a step further with his diet.
Rather than fully committing to a traditional clean bulk or disciplined nutrition plan, he described his approach as eating “half healthy” — splitting his meals and drinks between foods designed to help build muscle and foods that… definitely weren’t.
Naturally, one major question quickly came up.
If he’s eating normally, how can he guarantee the nutrients are only helping one side of his body?
James had an answer for that.
Sort of.
“That’s a great question … the answer is I’m not.”
That pretty much summed up the spirit of the whole experiment.
It was part science, part chaos, and fully committed.
As the weeks rolled on, the visual changes were harder to spot than many expected.
Given the extreme nature of the challenge, you’d assume there would be an obvious imbalance — one arm bulging out of T-shirts while the other looked untouched.
But when James checked his progress in the mirror, the differences weren’t nearly as dramatic as people might think.
Aesthetically, there wasn’t a huge gap.
At first glance, both sides still looked fairly similar.
That alone was surprising.
Because after 100 days of targeted work, many would expect one side to be visibly ahead.
But while the mirror wasn’t screaming “success,” the strength tests told a completely different story.
And that’s where things got interesting.
To measure the difference, James tested his side plank endurance on both sides.
First up was his untrained side — the weaker half.
He managed one minute and 14 seconds. Not bad.
Then came the side he’d spent over three months hammering.
On his trained side, James held the plank for a staggering four minutes. More than triple the time. A massive jump.
For him, that was the clearest proof the experiment had worked.
“That was one of my original goals at the start of this video ticked off,” he said, “but I think it’s fair to say that even if there’s not much difference in the way my abs look, there is so much difference in the strength of them.”
Featured image credit: James Chewbonic / YouTube
