Paul Rudd followed a "horrible" and "restrictive" diet while training for 'Ant-Man'.

The 54-year-old actor revealed the eating regime he followed was so strict, that he allowed himself some sparkling water as a treat.

Speaking on the 'Off Menu' podcast, he said: "When I was having to train for the 'Ant-Man' movie, and I was on a very restrictive diet, my reward was sparkling water. That’s how horrible that diet was. I was like, ‘Alright, I’m gonna have some sparkling water now, I’ve earned it.’”

And, Paul revealed he stuck to a strict diet when training for all of his Marvel movies.

He said: "Once you’re in it, it’s actually not too hard,” explaining that he didn’t mind having “really boring food, every time, over and over again,” as he would wake up with “tons of energy".

Comparing his training and diet to other actors in the Marvel Cinematic Universe, he said: "I think I worked out harder than anyone, I would eat better than everyone, and I looked worse than all of them. I had to work out all the time, eat perfectly, just to look kind of bad. Not even like great.

"I remember on 'Endgame', Chris Hemsworth would always have these Tupperware containers and he’s eating this gruel of just a mash of stuff. He’s working out, and then you stand next to a guy like that, and I just think, ‘Well, what’s the point of any of this?’ Why am I killing myself when that can exist, and then I look at myself and this exists. I can never achieve that. … That was the good thing that it was 'Ant-Man', it isn’t 'Thor'. But I tried to work out, and it didn’t work."