Yo-yo dieting – just say no. Easy enough when you're a normal person, unlikely ever to be asked to drop a quarter of your bodyweight for professional purposes, but what if that weight loss is the difference between getting a job and losing it?
Actors, much like models and musicians and anyone else whose appearance plays a significant role in their career, will always be under pressure to stay in shape. But actors face the unique challenge of believably transforming into a different person for each new gig, and thanks to the nature of talent deals and pre-production schedules, they're often given only a few weeks' notice to make the shift.
Dramatic physical transformations also have a reputation as Oscar bait, and it's true that a fair number of Academy Awards for acting have been handed out for roles that required an actor to either bulk up, starve down, or look ugly. But there's now a pretty substantial body of anecdotal evidence to suggest that starving yourself – or, indeed, gorging yourself – for a short-term physical look could have long-term health implications.
Take Christian Bale, who's been deservedly dubbed "the king of Hollywood yo-yo dieting". Back in 2003, he lost 63 pounds to play a chronic insomniac in psychological thriller The Machinist, subsisting on a diet of coffee, apples and canned tuna, and going against the advice of medical professionals who advised him to stop at 130 pounds. By the time filming started Bale weighed somewhere between 110 and 120 (reports vary), and his co-star Michael Ironside has a story about this that will haunt you for months – suffice it to say, he lost so much weight that his body began to burn muscle in place of fat.
As if that weren't enough, he went right from The Machinist into prep for Batman Begins, re-gaining his lost weight and packing on muscle to get into 220lb superhero shape. A year later, he lost 55 pounds to play a stranded fighter pilot in 2006's Rescue Dawn. He dropped 30 pounds to play a drug-addicted boxer in 2010's The Fighter, and most recently gained 43 to play a paunchy con artist in American Hustle.
"The risks of drastic, rapid weight loss includes the loss of muscle mass and muscle strength, hormone or electrolyte imbalances, malnutrition, organ dysfunction, dizziness, and mood swings," warns Jennifer McDaniel, Spokesperson for the Academy of Nutrition & Dietetics. "In addition, repeatedly losing and gaining weight usually results in a high body fat percentage, lower resting metabolic rate, and less responsive hunger and satiety hormones."
Earlier this year, Bale dropped out of playing Enzo Ferrari in a Michael Mann-directed biopic, specifically because he couldn't safely gain the necessary weight in time. Even he had a limit.
"It gets worse every time you do it," says Dr Christine Ren-Fielding, chief of Bariatric Surgery at NYU Langone Medical Center. "Every time you lose weight, there's a rebound effect – the body will give you more cravings and more hunger signals, you will want to eat more carbs, and you can easily end up regaining more weight than you lost. Similarly if you gain weight and then lose it, you may have trouble going back to your previous lean weight, because the body has re-set its preferred baseline."
There are three types of weight you can lose, she explains – water, muscle or fat – and while fat is the healthiest to lose, it's not always the first to go, especially in people like actors who don't have much of it to begin with. "The body will always want to preserve fat, so if you're losing more than 10 pounds in a month, you're going to be losing muscle and fat together. That's the unhealthy part, when you start losing muscle mass."
Why is muscle loss such bad news? Aside from the obvious (you're weaker, less toned and more jiggly), research shows that the more muscle you lose, the more fat you re-gain when you go back to eating normally. "The loss of muscle mass triggers more hormones to drive fat re-gain, and what we call fat overshooting," says Dr Caroline Apovian, director of the Boston Medical Nutrition and Weight Management Center. Fat overshooting is exactly what it sounds like – after a period of weight loss the body goes into overdrive trying to recover what it's lost, and tends to over-compensate.
While there's no evidence that Bale has any lasting metabolic issues, he did experience exactly this kind of accelerated weight gain after The Machinist. "I got very sick during that time," he has admitted, "but I enjoyed getting sick. I didn't mind it at all. In that short amount of time I did actually go from 121 right back up to 180, which is way too fast, so that resulted in some doctor visits to get things sorted out."
"When you're calorie restricting, the body will cut down its metabolism by 400 calories a day on average," warns Dr Ren-Fielding. That means that when a person goes back to their regular diet, they may struggle to stop gaining weight because their body has adapted to burning fewer calories. "If an actor already has a predisposition to be overweight or has it in their family, then they should be very cautious about taking a role where they have to gain weight."
Many were shocked in 2013 when Tom Hanks announced he had type 2 diabetes, and suggested that his history of yo-yo dieting for roles could have contributed. In the early nineties Hanks gained 30 pounds for baseball classic A League of Their Own, and after returning to normal weight he lost another 30 pounds for Philadelphia. Jonathan Demme's drama about an AIDS patient suing his firm for wrongful dismissal would win Hanks his first Oscar. Eight years later, Hanks dropped 55 pounds to play the eponymous role in Cast Away, having first put on weight to look schlubby and middle-aged.
"The gaining and the losing of weight may have had something to do with [the diagnosis]," Hanks told David Letterman. "You eat so much bad food and you don't take any exercise when you're heavy. But I think I was genetically inclined to get it." McDaniels agrees that with a predisposition, yo-yo dieting could indeed trigger diabetes: "The increased body fat percentage with weight loss and weight regain could contribute to insulin resistance and inflammation, setting the stage for impaired blood sugar control."
Renee Zellweger, who has gained weight twice to play everybody's favorite singleton Bridget Jones, admitted that she "had a panic attack with all the specialists talking about how bad this is for you. Long term, putting on that much weight in short periods of time and they're all saying, 'You must stop this now or you're going to die'." Zellweger reprises her role for the upcoming Bridget Jones's Baby, but declined to gain weight again, so her slimmer frame was written into the script. "We all really loved the notion that Bridget, 15 years on, had finally reached her ideal weight," said director Sharon Maguire – but that's a creative decision that wouldn't have been made without Zellweger drawing the line.
Perhaps unsurprisingly, actors are more eager to talk about the perils of weight gain than weight loss. Jared Leto gained 67 pounds to play John Lennon's killer Mark Chapman in a 2007 biopic, and ended up with gout. "It's a stupid thing to do," he told The Guardian. "I got gout, and my cholesterol went up so fast in such a short time that my doctors wanted to put me on Lipitor, which is for much, much older people."
But risky though sudden weight gain can be, McDaniel suggests rapid weight loss is still the more dangerous option: "The electrolyte imbalance or stress on the heart can actually be life threatening in extreme cases." The most dramatic recent example of an actor starving for their art is Matthew McConaughey, who lost 40 pounds to play a man with full-blown AIDS in 2013's Dallas Buyers Club. Despite McConaughey's alarming appearance in the movie – he weighed 143 pounds at 6 feet tall – he was sanguine in interviews about the health effects he'd suffered.
"It changed my life for four months, but I didn't really run into any health issues. I just lost a lot of power and strength, but I found it actually made my mind sharper," he said. Oh, and he started going blind. "I would do five push-ups and be sore, I would run 30 feet and my legs would lock up, and as soon as I hit 143, I started losing my eyesight," he told Metro in 2013. "I'm still working on getting it back fully now." So… there's that.
Actors are not like the rest of us, and treating their bodies like a blank canvas comes with the territory. But Apovian says there are lessons to be learned from them, drawing a comparison between actors losing weight for a role and ordinary people who are already at a healthy weight, but still diet obsessively. "There are people who are lean, but think that they are overweight and so restrict their calories – this includes a lot of younger people, and people with eating disorders. These are the people who tend to yo-yo more than a few times, and stand to lose their metabolic advantage and lose their health."
"This is where art mimics life," Dr Ren-Fielding agrees, suggesting that in this way actors can serve as cautionary tales for the rest of us. "These artists are doing something to their body that actually happens to a lot of people in reality."