When Jasmine Norman was 11, she was diagnosed with hypothyroidism. The condition slowed down her metabolism and she put on a lot of weight.

"I just kept getting bigger and bigger, my thyroid levels never remained stable enough," Jasmine recalls.

She rapidly gained weight through her teen years, wanting "to go out and eat all the crap food like every teenager."

Jasmine tried a number of diets but nothing worked. She hated having to avoid all the foods her friends were eating. At 308lbs by age 24, Jasmine began to hider herself under baggy clothing.

Jasmine was the victim of a violent armed robbery, which challenged her to change her life.

"I hadn't had a chance to be able to take care of myself for a very long time," she said. "That was the one thing I could do for me and my health, that was something I could do for myself and regain part of who I was again."

Jasmine signed up for the MyFitnessPal app and tracked everything she ate, limiting herself to 1,200 calories a day. She started going to the gym every day, hiking, and making sure she was eating properly.

Jasmine went from 308lbs to 172 in a matter of months, all thanks to an app on her phone.

Jasmine says she won't feel fully satisfied until she has surgery to remove the excess skin, but she's not letting that derail her success.

She also makes it clear that dieting is all about moderation.

"I don't believe it's a way of living if you don't enjoy your life," she said. "The best thing I could do is to give [motivation] to someone who didn't think they could do it. I'm proof that you can. It's hard, but you definitely can."