Harvey Diamond is the co-author of the #1 New York Times bestseller, Fit for Life, which has sold over 12 million copies worldwide and been translated into 33 languages. Internationally known as an author, teacher, and health consultant, he has appeared on hundreds of radio and TV programs including Larry King Live, Oprah!, Nightline, and Good Morning America.
Fit for Life (FFL) is a diet and lifestyle book series stemming from the principles of Natural Hygiene. It is promoted mainly by the American writers Harvey and Marilyn Diamond. The Fit for Life book series recommends dietary principles including eating only fruit in the morning, eating predominantly "live" and "high-water-content" food, and if eating animal protein to avoid combining it with complex carbohydrates.