Zac Efron and Hugh Jackman have spoken about the move in the past.

Between The Odyssey and the new Spider-Man installation, Brand New Day, Tom Holland has been working pretty hard on his new movies. 

And for the Marvel flick, that graft includes a rigorous workout routine.

The actor’s trainer, Duffy Gaver, has previously shared the brutal “ladder” routine that helped the star to get into “crazy shape” for the franchise.

But in a recent appearance on Waitrose’s Dish podcast, Tom said that the most brutal prep for his recent film had nothing to do with pull-ups.  

“I tried to do that whole like dehydration thing,” he explained to hosts Angela Hartnett and Nick Grimshaw.

“It’s like what athletes do – to try and lose weight really quickly. But one of the side effects of it is it really accentuates the work you’ve been doing in the gym.”

Some sportspeople, like bodybuilders, dramatically cut their water consumption right before competing. This sometimes gives the appearance of a leaner physique, but it doesn’t make you lose any actual fat – and we hope we don’t need to tell you that dehydrating yourself is not good for your health at all.

Per the NHS Royal Devon University Healthcare, dehydration can sometimes make people “seriously ill”, possibly even leading to kidney issues.

Nonetheless, actors have long tried the trick for topless scenes.

Hugh Jackman, who was working on another Marvel movie Wolverine at the time, told Stephen Colbert: “You increase your water intake to, like – I’m trying to think what the gallons is – but you have about 10 litres of water, which is, what? Three gallons of water a day?

“And then you stop about 36 hours before you shoot. But, because you’ve drunk so much water, you are peeing, all the time.” 

Zac Efron, meanwhile, who starred in the 2017 Baywatch movie, revealed to Men’s Health: “That Baywatch look, I don’t know if that’s really attainable. There’s just too little water in the skin. Like, it’s fake; it looks CGI’d.

“And that required Lasix, powerful diuretics [medicine that makes you pee] to achieve. So I don’t need to do that. I much prefer to have an extra, you know, two to three percent body fat.”

For Tom, though (who was presumably supervised while making the step), the method didn’t give him the desired effect at all.

When it came to giving his muscles a more defined look, “For me, it didn’t do any of that,” the star said.

“It just really pissed me off because I was so thirsty.”

You can listen to the entire Dish podcast here.