Tom Hardy has "damaged" his body by bulking up for movie roles.

Tom Hardy

Tom Hardy

The 39-year-old actor is concerned his body will "collapse" if he has to gain weight for a part again and he admits he is getting to old to consider physical transformations to the extent he underwent when playing an MMA fighter in 'Warrior' and Bane in 'The Dark Knight Rises'.

Asked if he'll need to bulk up to play Al Capone in 'Fonzo', he said: "It's not the classic Al Capone that you necessarily envision with the silhouette. I don't want to give too much away about it, but there's definitely a transformation with that role.

"I don't know if it's as drastic as Bane. I've probably damaged my body too much. I'm only little!

"If I keep putting on weight I'll collapse like a house of cards under too much pressure.

"I think you pay the price with any drastic physical changes. It was alright when I was younger, to put myself under that kind of duress, but I think as you get into your 40s you have to be more mindful of the rapid training, packing on a lot of weight and getting physical, and then not having enough time to keep training because you're busy filming, so your body is swimming in two different directions at the same time.

"And then after the film I'm tired, and you maybe have to change your shape again and go back to your normal size for the next film. To go from one extreme to another has a cost."

And Tom - who has son Louis, eight, from a previous relationship and

a 15-month-old baby with wife Charlotte Riley - admits the physical discomfort makes it tricky for him to pick up his kids.

He added in an interview with The Daily Beast: "I'm certainly a bit achier than I used to be! I kind of miss it.

"Compared to Christian Bale I've been by no means extreme in my body changes, but for what little I've done, yeah,

"I certainly have joints that click that probably shouldn't click, you know what I mean? And I carrying my children is a little bit harder than it used to be--but don't tell them!"