John David Weinroth (born April 20, 1968), known professionally as J.D. Roth, is an American TV producer, actor, voice actor, and game show host, and TV personality. Roth has been involved in numerous TV shows. He is the co-creator of the reality show The Biggest Loser on NBC. He also hosted ABC's fall 2008 series Opportunity Knocks. He served as the announcer of the ABC tv show, Extreme Weight Loss.