There is no denying that the morbid fascination of watching a celebrity undergo an extreme body transformation can make a film all the more appealing to moviegoers, but when do they push stars too far?
Whether it's cramming 10 big macs into you pie hole everyday to pile on the pounds or barely surviving on tiny scraps of sustenance, extreme weight gain or loss puts a huge toll on the body that really proves an actor's dedication to their role.
Each of these 15 actors underwent insane weight changes for movies, but what exactly did they eat to achieve it? Let's take a look...
1. Anne Hathaway - 'Les Miserablés'
Weight Lost: 25lb
Diet: Only leaves and green vegetables
"I was on a starvation diet to look like I was near death in a film... but I went at it with a plan and I had a guide, a nutritionist kind of helped me with it.
I just had to stop eating for a total of 13 days shooting."
2. Christian Bale - 'The Machinist'
Weight Lost: 63lbs
Diet: Tuna, apple, coffee
"I have no goal of seeing if I can become invisible one day, eat so little that I disappear. I didn't take this job because I went, 'Oh, there's a physical transformation needed.' I always go, 'Damn! There's a physical transformation needed!'"
3. Matthew McConaughey - 'Dallas Buyers Club'
Weight Lost: 47lbs
Diet: Diet Coke, egg whites, chicken
“That was rough. I got down to 143lbs and I was always hungry, and irritable. My body resembled a baby bird with its mouth open, crying, ‘Feed me, feed me,’ and you realize momma bird ain’t going to feed you. It’s hard.”
4. Tom Hanks - 'Castaway'
Weight Lost: 50lbs
Diet: Crabs, coconuts, and coconut milk
"The hardest thing was the time. I wish I could have just taken a pill and lost all the weight but the reality was that I had to start in October knowing that we were going to go back in February. The idea of looking at four months of constant vigilance as far as what I ate, as well as two hours a day in the gym doing nothing but a monotonous kind of work-out, that was formidable. You have to power yourself through it almost by some sort of meditation trickery. It’s not glamorous.”
5. Jake Gyllenhaal - 'Nightcrawler'
Weight Lost: 30lbs
Diet: Chewing gum, almond tea, and small bites of meat, crackers, and kale.
“There was a general sense that he was a coyote. I just wanted to live that way.”
6. 50 Cent - 'Things Fall Apart'
Weight Loss: 54lbs
Diet: 2 month liquid diet
"I had so much muscle on me that it was hard for me to lose definition even as I got lighter and slimmer. I started running to suppress my appetite. Towards the end it was really difficult. It was like, if I don't get close enough to what my best friend looked like to me at that point before he passed, then I'm not doing the story any justice."
7. Chris Hemsworth - 'In The Heart of The Sea'
Weight Loss: 15lbs
Diet: Boiled eggs, salads, and "nothing much."
"The gaining is fine, you just eat a lot and you lift weights but that was underfed, which led to a pretty moody existence and inconsistent emotions."
8. Matt Damon - 'Courage Under Fire'
Weight Loss: 40lbs
Diet: Egg whites, one plain baked potato, and one chicken breast per day
"I had to be thin and went on an unsupervised diet which could have killed me... A doctor told me later I could have shrunk my heart permanently. I am 5ft 11in and went down to 135lb from my usual weight, between 173lb and 176lb. It didn't do me any good."
9. Renee Zellweger - 'Bridget Jones's Diary'
Weight Gain: 20lbs
Diet: 4,000 calories a day
"For two days it's bliss and then you're full, OK? And you can then indulge all your fantasies about over-eating. Fantasies about non-stop chocolate consumption or your fantasies about ordering the pizza and the spaghetti and the garlic bread.
"Then after a week your glucose levels are going crazy. You're up and down and all over the place. It doesn't feel good, and no one wants to hear that, but it's the truth."
10. Charlize Theron - 'Monster'
Weight Gain: 30lbs
Diet: Salt, salt, and more salt.
“I first began stuffing myself with Krispy Kreme doughnuts, but after a while I got sick of them. I love potato chips, so that was a good thing for me. I’m a salty girl so I had my secret stash with me of potato chips at all times.”
11. Matthew Fox - 'Alex Cross'
Weight Loss: 44lbs
Diet: Chicken breasts, steamed broccoli, and protein shakes
"There were certain scenes in the film where for a week or 10 days beforehand it was really hardcore: as little as 1,100kcal or 1,200kcal a day. I was only eating chicken breasts, steamed broccoli and protein shakes made with water. That was brutal."
12. Jared Leto - 'Chapter 27'
Weight Gain: 67lbs
Diet: Drinking melted Häagen Dazs, mixed with olive oil and soy sauce.
“[I did it by] eating everything you think you're not supposed to—pizza, pasta, ice cream, but my little trick was I would take pints of chocolate Häagen Dazs and put them in the microwave and drink them.
“The sick thing is, I would actually pour olive oil and soy sauce into the mixture as well—to get me bloated even more.”
13. Natalie Portman - 'Black Swan'
Weight Loss: 20lbs
Diet: Little more than carrots and almonds
"There were some nights that I thought I literally was going to die. It was the first time I understood how you could get so wrapped up in a role that it could sort of take you down."
14. Tom Hardy - 'Bronson'
Weight Gain: 43lbs
Diet: Rice, chicken, full fat coke, pizza, and chocolate
"For Bronson I just ate chocolate and pizza, lifted Pnut [Hardy's personal trainer] up and down the stairs, played Xbox, shaved my head and grew a moustache."
15. Russell Crowe - 'Body of Lies'
Weight Gain: 63lbs
Diet: Bring on the burgers, baby!
“If you want to put on weight, you just elect to live a sedentary life style. Just as soon as you stop actually being active and decide to eat what ever you want, then these two things will combine very quickly.”