"When he left he said all he wanted was a minivan out of the show," Britt, 22, tells PEOPLE. "I promised him if I won I would get a minivan. So I owe Buddy a minivan."
Britt lost 199 lbs. (more than half his body weight) during the course of the competition. And he says he wouldn't have been able to do it without the help of his family, including his sister and fellow contestant Conda Britt, who lost 115 lbs. and also made it to the finals.
"When me and my sister went home we went to a great gym," Britt said. "My mom couldn't have been more supportive of me. She helped me out a ton."
Added Britt: "I'm not here where I am today without the help of my mom, my trainers back home, my trainers on the show, the gym. Everyone was so accommodating to me, and everyone needed a smooth transition and wanted to make it known – 'Jeremy, you make this about you and we will help you in any way we can.' That's how I got those results."
And the assistance has gone both ways, according to Jeremy.
"I do come from an overweight family, and my mom has lost 50 lbs. since we left for the show," Britt told PEOPLE. "To me, that's what it's about. I was given a great gift so I want to help other people, and being able to start with my own family is great."
Runner-up Kim Nielsen, a former professional wrestler, told PEOPLE she's replaced eating with shopping and has become a "mall addict" since losing 118 lbs. in the competition.
"It is so much fun to actually walk into a place and have someone hand me a size 4 or a size 2," Nielsen, 38, said. "That's ridiculous. I haven't been that small since I was, like, 10 years old. It's fun."
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