Chris Hemsworth would rather gain weight than lose it.

The 31-year-old actor has transformed his physique by bulking up or slimming down for a number of roles and though there are advantages and disadvantages to both, he prefers to pile on the pounds.

He said: ''It's the accordion effect which is the worst part. First I had to gain 20lbs of muscle mass for 'Thor' and then I had to lose all that, plus another 20lbs to play my character in 'Heart of the Sea'.

''I'd rather put weight on than take it off, but they both have their plusses and minuses.

''It comes back a little easier each time, the muscle memory. But you go from one extreme to the other, whatever that is, eating nothing or eating everything. Neither is particularly comfortable.''

And the 'Avengers: Age of Ultron' star hates the bland diets he has to go on when preparing for a new role.

He told Sorted magazine: ''After all that dieting, if I see one more serving of chicken breast with biologically grown broccoli, I swear that I'm going to take Thor's hammer to the plate.''

Chris found it particularly tough shedding the pounds for 'Heart of the Sea', which he began filming shortly after completing work on 'Blackhat'.

He said: ''I did Michael Mann's movie ['Blackhat'] right before I started with Ron [Howard] and I'd started to lose weight at the beginning of that.

''By the time I got to Ron's film, eight, nine months after, I was exhausted and, by the end, dead.''