James David Weinroth (born April 20, 1968), known professionally as J.D. Roth, is an American television producer, actor, voice actor, game show host, and television personality. Roth is the co-creator of the reality show The Biggest Loser on NBC and the ABC reality TV show, Extreme Weight Loss (as well as the narrator). His hosting jobs include ABC's fall 2008 series Opportunity Knocks, the Fox adult reality game show Unan1mous, the children's reality show Endurance on NBC and the Discovery Kids Channel, and the children's game show Fun House which aired on Fox and in syndication.