Scott Mitchell, the former NFL quarterback most famous for playing with the Detroit Lions, tackled a new challenge when he appeared as a contestant on NBC's The Biggest Loser. 

The 47-year-old Mitchell has battled weight problems since retiring from the NFL in 2001. He took part in the show's 16th season, which is currently airing, and has had a rapid transformation. 

According to Us Weekly, Mitchell started the show weighing in at 366 pounds and after 15 weeks has lost over 100 pounds:

Mitchell, who played 12 seasons in the NFL for teams including the Detroit Lions and Baltimore Ravens, started The Biggest Loser at 366 pounds. Motivated by his father's death of obesity-related causes earlier this year, he joined the show so he could be healthy for his children.

Four months later, the ex-athlete is 124 pounds lighter. 'It's weird to put on clothes that can button!' Mitchell told Us of his new body. 

Us Weekly also tweeted out a picture of how drastic Mitchell's weight-loss transformation turned out to be:

Us Weekly @usweekly

Wow! Scott Mitchell's #BiggestLoser makeover is a must-see. Watch the clip:

If you aren't familiar with the show, contestants are separated from their families during the process. They are given different challenges each week and have to meet a certain weight-loss goal or risk being voted out of the competition. 

In an interview with Frazier Moore of The Associated Press, via The Baltimore Sun, Mitchell talked about his struggles with gaining weight during his playing days:

I really struggled with my weight during my playing career. When I retired in 2001, there were no more football seasons to get ready for. I had worked out because of my job, and after retiring I kind of resented exercise because of that. So I just slowly put on weight.

...

Once I got there, they said, 'You're gonna lose weight, but you'll gain it all back unless you figure out why you gained it in the first place.'

Even though Mitchell became a punchline for how he got a big contract from the Lions after a successful turn as Dan Marino's backup in Miami, this is a story that transcends anything he did on the football field. He found an avenue to turn his story into a positive, uplifting moment for himself, his family and everyone watching. 

Considering Mitchell mentioned having struggles keeping weight off in the past, hopefully he's found a regimen that allows him to stay on the path that he's set for himself. It won't be easy, but playing in the NFL taught him what it means to face adversity.