While Hollywood today is more than capable of letting actors put on and shed pounds from scene to scene thanks to computer-generated imagery, certain actors would rather clock hours at the gym to get in shape for their next big role. 

There is just something about knowing an actor worked extra hard to better portray their role that makes us appreciate the finished product a little more than we already do. 

Here are five actors that underwent a weight loss transformation for movie roles. 

1. Matthew McConaughey for 'Dallas Buyer's Club'

McConaughey played the part of a man diagnosed with HIV/AIDS for the movie Dallas Buyer's Club. The actor lost a whopping thirty-eight pounds for the role. 

Right before the five-week shoot kicked off, the actor opened up about his transformation to Hitfix. According to him, getting below 170 pounds was especially difficult. 

However, once he got down to about 167 lbs, the next seven pounds just fell right off. Again, getting past 160 was hard, but once he reached 150, he got to his ideal 143 lbs fairly easily. 

2. 50 Cent for ‘Things Fall Apart’

Rapper 50 Cent was also set to portray a severely ill patient for the movie Things Fall Apart. In his case, it was cancer. The actor supposedly took up the challenge as a tribute to a friend who died of the disease. 

For his part, the actor lost a massive fifty pounds off his buffed-up frame for the second leg of the movie. He told Huffington Post that it was hard for him to lose definition even when he lost weight because he had so much muscle to begin with. 

The rapper dropped from a healthy 214 lbs to 160 lbs in nine weeks by switching to a liquid diet and running on a treadmill three hours a day. Before that, the rapper had gotten down to 157 pounds when he was shot in the jaw back in the year 2000. 

3. Chris Hemsworth for ‘In The Heart Of The Sea’

Much like the rapper, when one thinks of Chris Hemsworth, the imagination jumps straight to the buffed-up God of Thunder, Thor, which he plays for the Marvel Cinematic Universe. One might have a hard time coming up with an image of a skinny Hemsworth in their minds. 

Still, for the movie, He lost 33 lbs for the role, and his diet was at times limited to a single egg a day. 

His character was supposed to be accompanied by other crew members on the sea for 90 days as they struggle to overpower a sperm whale that killed off many of the men on board. 

4. Christian Bale for ‘The Machinist’

One cannot talk about astonishing weight loss in Hollywood without including Christian Bale's transformation for The Machinist. 

He shed over 55 pounds in a four-month window to play the insomniac industrial worker. He was on a diet of cigarettes, whiskey, black coffee, a solitary apple, and a can of tuna during his transformation. 

In a conversation with GQ, he said, 

I've become a little bit more boring now, because I'm older and I feel like if I keep doing what I've done in the past I'm going to die. So, I'd prefer not to die.

5. Adam Driver for ‘Silence’

Capping the list off is Adam Driver's portrayal of a 17th century Portuguese Jesuit priest traveling from Portugal to Japan to locate his mentor in the movie Silence.

The story made his character suffer through disease and a shortage of food during the journey. 

Despite the challenging experience, the actor told People that the overwhelming hunger actually helped him deliver a more raw and authentic performance.

He also disclosed that his director wanted him to "lose a lot of weight" and did not give him a number. So, he continued to lose weight throughout the movie.