Jillian Michaels is best known as a strength trainer and life coach for NBC's hit series The Biggest Loser. Her passion for fitness training originates from seventeen years of martial arts practice in Muay Thai and Akarui-do, in which she holds a black belt. Since 1993, Jillian has held two personal training certificates from the leading certification programs in the country, the National Endurance and Strength Training Association (NESTA) and the American Fitness Association of America (AFAA). Mariska van Aalst is a researcher and writer who has coauthored You Say More Than You Think; The Doctors 5-Minute Health Fixes: The Prescription for a Lifetime of Great Health; and Jillian Michaels’s New York Times bestselling Master Your Metabolism: The 3 Diet Secrets to Naturally Balancing Your Hormones for a Hot and Healthy Body!