Jake Gyllenhaal put on 45 pounds of muscle in six months to portray a boxer in the film Southpaw and he's garnered praise for dedicating himself to the role. But it's possible — very possible, say bodybuilders — that he used performance-enhancing drugs to achieve this impressive physical change. 

Depending on a person's beginning fitness level, weightlifters put the maximum amount of potential muscle gain at two pounds per month. But that's too long a waiting period for actors who need to beef up for a shoot.

In an industry that prizes youthful qualities, Hollywood stars are no strangers to taking steroids. Sylvester Stallone, for example, was caught red-handed entering Austria with vials of Human Growth Hormone and testosterone. And Gyllenhaal's trainer estimates that about 20 percent of male leads in Hollywood are doping.

At the University of Oxford's Practical Ethics blog, Chris Gyngell, a postdoctoral research fellow in neuroethics, argues that our criticism of athletes who use performance enhancers doesn't square well with our laissez-faire approach toward actors. In other words, if we think it's immoral for athletes to engage in doping, it should also be immoral for actors. Here's why:

It's unfair.

Because steroids are illegal, actors (and athletes) who use them gain an unfair advantage over those who do not break the rules. That's a clear ethical standard, says Gyngell.

It's unsafe.

If we value public health, we should enforce rules that restrict the use of steroids known to increase the risk of heart attack. Safety shouldn't just apply to athletes. There is as much incentive for actors to engage in risky behavior due to the money on offer for certain roles.

It's against the spirit of the craft.

Sports are transparently about even-handed competition. It may seem less so with acting. But when it comes to examining human character and revealing what an actor finds in front of a camera, do we want individuals willing to skirt the rules telling us about fundamental human truths?

As Gyngell concludes, we should take a closer look at our willingness to excuse actors who use illegal performance-enhancing drugs while being harsh critics of athletes who do the same.

Photo credit: Michael Loccisano / Getty Staff