Not every shredded celebrity has always been shredded. In fact, some of the most ripped guys in Hollywood started as skinny or even overweight. But when a big role comes along that requires some major changes, these guys are up for the task. We took a look at some of the best celebrity fitness transformations out there, and they’re pretty incredible changes.

Chris Hemsworth

What He Did: Hemsworth packed on 20 pounds of muscle by eating constantly.

Why He Did It: For his starring role in the action-packed blockbuster Thor.

What He Ate: Hemsworth opted for high-protein foods, but also relied on non-processed carbs like fruits to help rebuild muscle by slowing muscle protein breakdown. Fiber-rich vegetables helped his cardiovascular health and muscle recovery. He made sure that what he was eating counted, eating quinoa instead of rice since it has protein, healthy fats and fewer carbs.

His Workout: Before Thor, sports like surfing, boxing and rugby kept Hemsworth fit. But for the movie, he started getting serious about lifting, varying weight, reps and speed so that his muscles never got used to workouts. Even minor changes, such as swapping hand placement on a pull-up, can stimulate muscles in new ways. In fact, mixing things up is important no matter what kind of muscle gain you’re looking for.

Plus: Hemsworth bulked up so much that he didn’t fit in any of his costumes.

Chris Says: “I feel as if I’ve been busy, but all I’ve been doing is eating all day. Eating when you’re not hungry and taking in that amount of food is exhausting.” 

CREDIT: Men’s journal