Is “The 8 Hour Diet” really just “The Overnight Fast?”

Yesterday 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.

Here 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”

8 hour dietEat 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 enery
  • 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

In order to get the optimum results, you should eat at least one serving of each of 8 “superfoods” each day:

  1. Turkey, chicken, eggs, fish and other lean meats
  2. Walnuts and other nuts
  3. Yogurt and other dairy
  4. Beans, peanuts, and other legumes
  5. Raspberries and other berries
  6. Apple, oranges and other fruit
  7. Spinach and other green vegetable
  8. Whole-grain breads and cereals (including oatmeat)

The authors also encourage skipping breakfast (except for coffee or tea) and having lunch as the first meal of the day.

Exercise doesn’t need to be more than 8 minutes in the morning, before eating.  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.

The “Extras”

In contrast to The Virgin Diet, there aren’t a lot of “extras” promoted by The 8 Hour Diet authors, 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

mitochondria_cell_imageThe scientific theory of the diet is that allowing a 16 hour fast after an 8-hour eating period gives the mitochondria (sometimes called the cell’s powerhouse) the ability to function more efficiently. The book even claims that this fast promotes the production of more mitochondria in each cell.

The result of this is that you would burn calories more efficiently which leads to weight loss.

A second effect is that the mitochondria produce less of a byproduct of energy production called “free radicals.” Free radicals are what Zinczenko calls “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 this theory seems to rely on the studies by two scientists, Satchidananda Panda, PhD at the Salk Institute and Mark Mattson, PhD, chief of the Laboratory of Neurosciences at the U.S. National Institute on Aging (NIA).

pandaDr. Panda looked at two groups of mice. One group was only fed during an 8-hour window, the other ate whenever they wanted.  Although the two groups ate about the same amount of calories, the group that ate only during a fixed time period gained less weight than the other group.

Dr. Panda summarized his results by saying that each organ in the body has it’s own internal clock- each with periods of peak efficiency and rest. Furthermore:

When mice or people eat throughout the day and night, it can throw off those normal metabolic cycles.

mmattsonDr. Mattson’s 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. Although his research has shown that semi-starvation can boost stress-response proteins, which can protect cells from aging and disease, these studies have all been done in mice. Whether these results can translate as well to humans hasn’t yet been thoroughly studied.

The intermittent fasting (IF) movement 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 criticized it as a “ripped-off,” watered-down version of Martin Berkhan’s Leangains diet, which is primarily geared to bodybuilders.


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 Alzheimers and other chronic diseases.

This is one of the most exaggerated books I have ever read. Every line oozes with superlatives, each line of research is “groundbreaking” or has “rocked conventional weight-loss thinking to its core.” Even if there is some truth to the science behind the diet, the implied results are beyond fantastic.

Does it make sense that the guy who has promoted (in his Eat This Not That! series) eating one healthier option over fat- or sugar-laden ones should now tell you to go ahead and have that pizza, ice cream sundae or second 16-oz steak if you feel like it?


Michele R. Berman, M.D. was Clinical Director of The Pediatric Center, a private practice on Capitol Hill in Washington, D.C. from 1988-2000, and was named Outstanding Washington Physician by Washingtonian Magazine in 1999. She was a medical internet pioneer having established one of the first medical practice websites in 1997. Dr. Berman also authored a monthly column for Washington Parent Magazine.

Leave a Reply

Your email address will not be published.

Real Time Analytics Google Analytics Alternative