Fit for Life (FFL) is a diet and lifestyle book series stemming from the principles of orthopathy. It is promoted mainly by the American writers Harvey and Marilyn Diamond. The Fit for Life book series describes a fad diet which specifies 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.
While the diet has been praised for encouraging the consumption of raw fruits and vegetables, several other aspects of the diet have been disputed by dietitians and nutritionists, and the American Dietetic Association and the American Academy of Family Physicians list it as a fad diet.Cite error: A
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</ref> (see the help page).  which sold millions of copies, over 12 million according to Harvey Diamond. Harvey Diamond has also appeared on dozens of television talk shows promoting his theories. In Fit for Life II (1989) the Diamonds warned against eating artificial food additives such as hydrogenated vegetable oil, which at the time was being promoted by the food industry as a healthy alternative to saturated fat. Tony Robbins promoted the Fit for Life principles and veganism to increase energy levels in his book Unlimited Power.
- Fit for Life (1985) - by Harvey and Marilyn Diamond ISBN 0-446-30015-2
- Living Health (1987) - by Harvey and Marilyn Diamond ISBN 0-446-51281-8
- Fit for Life II (1989) - by Harvey and Marilyn Diamond ISBN 0-446-35875-4
- Fit for Life: A New Beginning (2001) - by Harvey Diamond ISBN 1-57566-718-5
- Fit for Life Not Fat For Life (2003) - by Harvey Diamond ISBN 978-0-7573-0113-1
- Living Without Pain (2007) - by Harvey Diamond ISBN 0-9769961-0-3
Additional books by Marilyn Diamond
- A New Way of Eating from the Fit for Life Kitchen (1987)
- The American Vegetarian Cookbook from the Fit for Life Kitchen (1990)
- The Fit for Life Cookbook (1991)
- Fitonics for Life (1996) with Donald Burton Schnell
- Recipes for Life (1998) with Lisa Neurith
- Young For Life (2013) with Donald Burton Schnell
The rigor of study underlying Harvey Diamond's credentials have been disputed, which has drawn questions about his competence to write about nutrition, because his doctoral degree came from the American College of Life Science, a non-accredited correspondence school founded in 1982 by T.C. Fry, who did not graduate high school or undergo a formal accreditation process himself. FFL's personalized diet program has been criticized for providing a "Clinical Manual" that is heavily infused with alternative medicine claims about how the body works, some of which may be scientifically inaccurate or not accepted by conventional medicine.
Despite the fact that FFL web site mentioned "clinical trials", many of the proposed principles and benefits of FFL diet are not supported by citations to any scholarly research, and some of the claims have actually been directly refuted by scientific research. For example, a dissociated diet as that advertised by FFL is no more effective for weight loss than a calorie-restricted diet.
- McDowell, Edwin (1988-01-06). "Best Sellers From 1987's Book Crop". New York Times. Retrieved 2009-02-09.
- Cite error: The named reference
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- Fein, Esther B. (1993-02-01). "THE MEDIA BUSINESS: Publishing; Where literary lightning hits, book houses often hope for a second strike". New York Times. Retrieved 2009-02-09.
- Diamond, Harvey (2003-11-17). Fit for life, not fat for life. HCI. p. 82. ISBN 978-0-7573-0113-1.
- Hines, Terence. (1988). Pseudoscience and the Paranormal: A Critical Examination of the Evidence. Prometheus Books. p. 254
- Butler, Kurt. (1992). A Consumer's Guide to "Alternative Medicine": A Close Look at Homeopathy, Acupuncture, Faith-healing, and Other Unconventional Treatments. Prometheus Books. p. 14. ISBN 0-87975-733-7
- "Fit For Life: Some Notes on the Book and Its Roots". Quackwatch.
- Golay A, Allaz AF, Ybarra J, et al. (April 2000). "Similar weight loss with low-energy food combining or balanced diets". Int. J. Obes. Relat. Metab. Disord. 24: 492–6. doi:10.1038/sj.ijo.0801185. PMID 10805507.