The Biggest Loser's Bob Harper is switching roles again.

NBC has announced Harper, who has served as a trainer on The Biggest Loser since its first season debuted back in Fall 2004, will be replacing Alison Sweeney as host of the reality weight loss competition.

Harper will be guiding contestants through Season 17's challenges, weigh-ins and temptations.

"I'm super excited about taking the position of host on The Biggest Loser," Harper said in a statement.

"I've been with the show since season one so I know all of the ins and outs, and let me tell you, the weigh-in room is going to be a completely different ballgame with me at the steering wheel."

However, Harper will still be training contestants at various points throughout the season, according to the network.

Last season, Harper starred in a different position for The Biggest Loser: Glory Days.

Each week, when a contestant got eliminated and believed he or she was going home, that person was actually whisked away to a secret location called "Comeback Canyon," where Harper served as the sole trainer. The contestants were given a second chance to re-enter the original Biggest Loser competition and vie for the $250,000 grand prize by secretly competing at separate weekly weigh-ins.

Dolvett Quince and Jennifer Widerstrom will also be returning for the seventeenth season as the official trainers. They will each be responsible for training eight teams of two contestants.

This will be Quince's sixth The Biggest Loser season and Widerstrom's second. Production on the new edition begins this month.

The Biggest Loser producers announced in late August that Sweeney is leaving the series after an "incredible run." She joined the show eight years ago back in 2007 for Season 4.

The Biggest Loser is produced by Endemol Shine North America and 25/7 Productions with Ben Silverman, Dave Broome, Eden Gaha, Alex Katz, Joel Relampagos, Michael Brooks, JD Roth and Todd A. Nelson serving as executive producers.