Australian actor Chris Hemsworth shocked fans this week when he tweeted a shirtless photo of himself that revealed drastic weight loss. The Thor-like brawn, flaxen hair, and megawatt smile that scored Hemsworth People magazine's "Sexiest Man Alive" title in 2014 are gone. What remains is an unrecognizably gaunt face, a caveman-esque mop and beard, and, most disturbingly, a spindly, starved frame with protruding ribs and collarbone.
Hemsworth underwent this transformation for his role in the upcoming movie In the Heart of the Sea, the true story that inspired Herman Melville's Moby Dick. In the film, he plays Owen Chase, first officer of an American vessel that collided with a giant sperm whale in the South Pacific in 1820. The 20-man crew is stranded at sea and resorts to cannibalism before Chase and seven others get rescued.
To make his character believable, Hemsworth had to look the part of a man desperate enough to eat his crewmates. The 32-year-old had reportedly already shed some of his Thor weight going into production. But getting Owen Chase–level emaciated required him to eat as few as 500 calories a day, which, as his photo makes clear, was a living hell: "Just tried a new diet/training program called 'Lost At Sea.' Wouldn't recommend it." Hemsworth has called the experience "brutal" and said he and his co-stars went insane, talking about nothing but dieting and losing weight.
This type of extreme weight loss isn't uncommon in Hollywood. Matthew McConaughey dropped 38 pounds to play a man diagnosed with HIV in Dallas Buyers Club. Christian Bale has whittled his body to next to nothing a few times, first for American Psycho and again for The Machinist.
Technically, it was part of the actors' job to get scarily skinny, and they no doubt took home a fat paycheck for their efforts. But drastic fat and muscle loss has far worse consequences than a skeletal appearance and hunger. "You pay such a high price for starving yourself like this," says Dr. Roxanne Sukol, a preventive medicine and nutrition expert at the Cleveland Clinic. "It's pretty simple, really: When you don't give your body fuel, your systems begin shutting down pretty quickly. Eventually, you'd die."
Hemsworth and his A-list colleagues haven't literally starved themselves to death, but their bodies were likely on that path. It only takes a few days of not eating enough food for your body to start going haywire, says Kate Zeratsky, RD, a nutrition expert at the Mayo Clinic.
Starvation kicks off a cascade of troublesome effects: In the absence of calories coming in, Zeratsky says the body, needing some source of energy, taps into the glucose stored up in fat, the liver, and muscle tissue. Once these reserves are burned through, however, it's forced to start shredding other tissues, mainly muscle, to create glucose. This process, called gluconeogenesis, churns up toxic compounds called ketone bodies that the kidneys, pancreas, and lungs must continually try to flush out. "Besides not being supplied the energy they need to work properly, your vital organs are constantly trying to correct everything that's going wrong in your body," Zeratsky says. "When there's not enough food and water coming in to help dilute these toxic ketone bodies, too much demand is placed on these organs."
Meanwhile, the heart takes a huge hit. It's not getting enough fuel to function properly and, because the heart is a muscle, it's also being chewed away for energy, says Zeratsky. The brain isn't faring well, either. Sukol says a lack of key electrolytes like potassium and sodium, which power the brain-nerve connections that tell the rest of the body to work, can lead to irreversible brain damage. And independent of not taking in enough calories, not getting a steady stream of fat, protein, vitamins, and other essential nutrients further inhibits brain, heart, and gut function, Sukol adds.
Then there's the emotional component. Just as the physical chaos is erupting within, starvation creates a disordered relationship between the brain and food, says Lisa Young, RD, an adjunct professor of nutrition at New York University. This is evident in Hemsworth's admission that all he and the guys thought about was eating, and when they couldn't eat, they obsessed over who got the thinnest. "Prolonged starvation is especially emotionally damaging," Young says. "Even after you start eating again, you can end up yo-yoing." That's because your body somewhat adjusts to the new normal of so few calories, changing your metabolism so that when you begin consuming enough, you can gain weight quickly.
All said, there's absolutely nothing to be gained — and a whole lot to lose — from slashing your food intake to this extreme. Down the road, these actors may find that even a multimillion-dollar paycheck wasn't worth it.