Chris Pratt used to be known as just Anna Faris' husband and the chubby funny man from "Parks and Recreation." He is also known for losing and gaining weight for roles but his transformation from dumpy Andy Dwyer to hunky Star Lord in "Guardians of the Galaxy" caught fans by surprise. 

The actor admitted to "Men's Health UK" that he purposely gained weight for his role of Andy. He recounted how he "would eat four burgers at every [script] read." His weight ballooned to 300 pounds but he said he was also at his funniest during that time.

However, the "Moneyball" star admitted that he "was impotent, fatigued, emotionally depressed" at the time he was at his heaviest. But seeing himself in "Zero Dark Thirty" gave the actor the impetus to really change his lifestyle and his approach to exercise and diet.

Changing his diet was a big challenge for the 36-year-old Pratt as his wife loves to cook. In Faris' own words, she loves "to cook big, fattening meals" like roast chicken and fried croutons. He started changing his diet by avoiding junk food first and by staying away from his favorite beer and wine. He also added more fruits, vegetables, seeds and nuts to his daily intake and ate only lean meats.

Exercise was also something that the Star Lord knew he had to do on a daily basis. So he enlisted one friend to work out with him. It turned out to be a great idea for him because it gave him a "feeling of accountability," especially since his workout friend Jared "is the kind of friend that when you say you're going to do something, you do it."

Pratt did different strength training exercises combined with cardio workouts every day. He focused on traditional body building exercises that targeted specific muscles during the first months of training. He then added circuit training and did P90X after several months.

One part of his "Guardians of the Galaxy" workout consisted of the following:

Warm-up:

Treadmill (10 minutes at 5.0 speed)

Pull-ups (3 sets, 5 reps)

Push-ups (3 sets, 10 reps)

Squats (3 sets, 15 reps)

Workout 1

Lat pull-downs (6 sets, reps of 140lbs x 20, 150lbs x 15, 185lbs x 15)

Dumb bell rows (5 sets, reps of 80lbs x 20, 90lbs x 15, 100lbs x 12)

Barbell curls (5 sets 75lbs x 15, 1 set 65lbs x 10, 5 push-ups after each set)

Dumb bell concentration curls ( 2 sets of 25lbs x 19, 1 set 25lbs x 9)

Chris Pratt's transformation did not come overnight, but the actor admits his hard work has paid off. Not only does he feel good, he has also motivated a lot of people into making changes too.

"I love the health benefits of exercising, and I have a kid now," he says. "By exercising, you really can add 20, 30 years to your life."