In our last post, we discussed one of the newest fad diets, The Virgin Diet, by J.J. Virgin. Today, we'll review The 8 Hour Diet by David Zinczenko and Peter Moore. Above is Zinczenko being interviewed by Today host Matt Lauer about the diet.
The Author
David Zinczenko is the former General Manager of Rodale Inc.'s Healthy Living Group and Editor-in-Chief of Men's Health. He authored the best-selling series, Eat This, Not That! and the Abs Diet. He is a regular contributor to the Today show and has appeared on Oprah, Good Morning America, Primetime Live, 20/20, The Rachael Ray Show, and The Ellen DeGeneres Show. Zinczencko's co-author, Peter Moore, is an editor and blogger at Men's Health Magazine.The "Hook"
Eat whatever you want, as much as you want as long as you only eat during an 8-hour period each day. The main claim is that you will lose weight (5-10 pounds in 6 weeks) even if you only follow the program as few as 3 days a week.
There are a lot of other exaggerated health claims in the book. For example, dieters will
- Shift the aging process into reverse
- Train their bodies to burn fat for energy
- Improve insulin sensitivity and dramatically decrease their diabetes risk
- Sharpen their minds and cut their risk of Alzheimer’s and other brain diseases
- Reduce free radical content and lower their cancer risk
- Reduce the inflammation that is the cause of so many chronic diseases
- Turkey, chicken, eggs, fish and other lean meats
- Walnuts and other nuts
- Yogurt and other dairy
- Beans, peanuts, and other legumes
- Raspberries and other berries
- Apple, oranges and other fruit
- Spinach and other green vegetables
- Whole-grain breads and cereals (including oatmeal)
Get it? The secret to diet and good health is 8-8-8: exercise for 8 minutes in the morning then eat 8 superfoods over the next 8 hours. For The Virgin Diet the answer was 7-7-7 or eliminating 7 intolerant foods to lose 7 pounds in 7 days. (Apparently these trios of identical digits have some miraculous powers -- do you remember presidential hopeful and pizza magnate to improve the U.S. tax code?)
The "Extras"
In contrast to The Virgin Diet, there aren't a lot of "extras" available (yet) for The 8-Hour Diet, other than a free exercise poster or walking guide. The diet is promoted heavily by Men's Health magazine, which encourages you to subscribe to their magazine when you purchase the book.The Evidence
The premise of the diet is that allowing a 16-hour fast after an 8-hour eating period gives mitochondria the ability to function more efficiently. The book also claims that this 16 hours fast promotes the production of more mitochondria in each cell. The result of this would be that you would burn calories more efficiently, which leads to weight loss.A second effect is that, with fasting, the mitochondria produce fewer free radicals, which Zinczenko refers to as "the source of almost all the ills in your body." Decreasing free radicals could reverse the aging process and prevent diseases such as Alzheimer's and diabetes.
The evidence for Zinczenko's diet seems to rely primarily on the studies of two scientists, of the Salk Institute and , Chief of the Laboratory of Neurosciences at the U.S. National Institute on Aging ().
Dr. Panda is an expert on the molecular mechanism of the biological clock in a mouse model system. In mammals, circadian rhythms are controlled not only by a central clock in the brain, but also by "subsidiary oscillators" in many peripheral tissues. Although the central clock is set by light and dark, the peripheral tissue clocks seem to be dependent on other factors, including feeding times.
Dr. Panda's studies in mice have shown that the liver appears to be one such place where peaks of efficiency and rest seem to be related to feeding and fasting. In a 2009 paper in Dr. Panda's group used wild and circadian deficient mice to study the relationship of liver gene expression to fasting and feeding cycles. They concluded that the temporal pattern of food intake played an important role in hepatic transcription (i.e. gene expression, RNA synthesis):
"If feeding time determines the activity of a large number of genes completely independent of the circadian clock, when you eat and fast each day will have a huge impact on your metabolism."
research deals with primarily with changes in brain at a cellular and molecular level during aging. He has also been a proponent of calorie restriction and intermittent fasting as a way to reverse some of the changes that aging causes. An excellent article reviewing this subject was written by Dr. Mattson for
We reached to Dr. Mattson about the claims made in the 8-Hour Diet, and this was his response:
"One of the authors, Peter Moore, interviewed me last year and I described the results of our animal studies on intermittent fasting, our two published studies on intermittent fasting in humans, and the science behind why intermittent fasting could improve health. I do not endorse any specific intermittent fasting regimen, because much more research is required in human subjects. Anyone considering an intermittent fasting diet should consult with their primary care physician.This book appears to be within the genre of the intermittent fasting (IF) movement, a pattern of eating that alternates between periods of fasting (usually meaning consumption of water and sometimes low-calorie drinks such as black coffee) and non-fasting. The length of the fasting period runs the gamut from fasting one day a week, to alternate-day fasting, to shorter periods of fasting with 8 hours being at the lower limit. Several reviewers of The 8 Hour Diet on Amazon.com criticized it as a "ripped-off," watered-down version of Martin Berkhan's which is primarily geared to bodybuilders.
To date, the scientific evidence that intermittent fasting can have many health benefits comes mostly from studies of overweight/obese animals and human subjects. The potential health benefits of intermittent fasting for normal-weight subjects remain to be determined. There are certain populations and medical conditions where fasting may cause harm, including very young children, the very old, and anyone who is underweight. While the results of studies of animal models of age-related human diseases are encouraging, there is as yet no evidence that long-term intermittent fasting can forestall specific diseases in humans."
Summary
The 8 Hour Diet is a diet based on intermittent fasting with 8 hours for eating, followed by a fast of 16 hours. The dieter should also eat at least one serving a day of each of 8 "superfoods." The authors claim that following the plan will cause weight loss, as well as reverse aging, prevent cancer and diabetes as well as Alzheimer's and other chronic diseases.On a stylistic note, this book is written in one of the most exaggerated manners I have ever read. Every line oozes with superlatives and each line of research is described as "groundbreaking" or having "rocked conventional weight-loss thinking to its core."
Even though there is some scientific rationale behind this diet, the claims made by the authors are extreme and premature. As the late, great science communicator and skeptic Carl Sagan used to say: "Extraordinary claims require extraordinary evidence." Both The Virgin Diet and The 8 Hour Diet make extraordinary claims based on only suggestive and anecdotal evidence.
For an informative summary of critical thinking tools and techniques, please see the Resounding Health .