Gabby Douglas

First African-American to Win Olympic Gold Medal for Gymnastics; Author of New York Times Bestseller "Grace, Gold & Glory: My Leap of Faith"

Bob Harper

Personal Trainer & Former Host of "The Biggest Loser;" Heart Attack Survivor

Maintaining A Healthy Body & Mind | Bob Harper Q&A

Jillian Michaels

Leading Fitness Expert, Certified Nutritionist, Renowned Life Coach & Powerful Entrepreneur

Richard Simmons

Fitness Instructor, Actor, Video Producer Known for "Sweatin' to the Oldies" Aerobics Videos

Sunny Anderson

Co-Host, Food Network's "The Kitchen"

Randy Jackson

Music Producer, Former "American Idol" Judge, Author & Health Advocate

Partha Nandi

CEO & Creator of "Ask Dr Nandi" & International Best Selling Author

Richard Sherman

Former All-Pro NFL Cornerback; NFL Analyst & Commentator; Co-host of 'Undisputed'

Ruben Studdard

American Idol Winner; The Biggest Loser Contestant; Dubbed the "Velvet Teddy Bear"

Keri Hilson

Singer, Songwriter & Actress; Known for "Knock You Down" and "Pretty Girl Rock"

Delta Burke

Actress & Comedian; Known For "Designing Women"

Peter Ubel

Behavioral Scientist Physician; Marketing Professor at Duke University

Tracey Mallett

Fitness and Wellness Expert; Creator of "The Booty Barre"

George Loewenstein

Herbert A. Simon Professor of Economics and Psychology at Carnegie Mellon University