Sometimes I just have to roll my eyes when I hear about nutritional experts rating diets. The reason is that apparently none of the “experts” actually reads the published data critically. Undoubtedly, one of the worst offenders is the annual U.S. News and World Report study on diets. After watching them year after year making the same unsupportable statements, I finally tried to educate the editors before the 2015 rankings appeared. Not surprisingly, I found all the same mistakes were still there.
Let me list what they wrote and my comments that I made to each of the sections that somehow never got included.
Will you lose weight?
What limited research there is on Zone suggests it’s moderately effective for weight loss.
- In another study of 160 people assigned to either Zone, Atkins, Weight Watchers, or the Ornish diet, weight loss was modest for all groups, according to findings published in the Journal of the American Medical Association in 2005. After one year the Zone dieters had lost an average of 7 pounds, compared with 7.3 for the Ornish group, 6.6 for Weight Watchers, and 4.6 for Atkins, and fewer Zone (and Weight Watchers) dieters had dropped out (about 35 percent) than Atkins and Ornish dieters (about 50 percent). About 25 percent of dieters in all groups had lost more than 5 percent of their initial body weight, and 10 percent had lost more than 10 percent of their starting weight. However, the Zone dieters were shown to have the greatest reduction in lowering inflammation.
- A study with 65 people assigned to either the Zone or high-carbohydrate diet with an equal number of calories was published in the Journal of Nutrition in 2009. Although the weight loss was similar in both groups, the fat loss was significantly greater for those on the Zone.
Does it have cardiovascular benefits?
Research is scant but does suggest that the Zone diet could help the heart by bringing down cholesterol levels and reducing inflammation.
- In the 2005 Journal of the American Medical Association study cited in the weight-loss section above, Zone dieters who completed the 12-month regimen reduced their total cholesterol by an average of 7 percent (not quite as dramatic as Ornish, slightly better than Weight Watchers, and much better than Atkins). Results were similar for “bad” LDL cholesterol: Down 13 percent for Zone, compared with 19 percent for Ornish and 10 percent for both Atkins and Weight Watchers. However, the Zone dieters had the greatest reduction in inflammation.
- In the 2009 Journal of Nutrition study cited in the weight-loss section above, Zone dieters had greater reductions in triglyceride levels and greater increases in HDL cholesterol levels than the subjects following a high-carbohydrate diet with equal levels of calories.
- A study published in the Journal of the American Medical Association in 2004 demonstrated that those following the Zone Diet had equal weight loss compared to those following a high-carbohydrate diet of equal number of calories, but the Zone subjects had a 900% greater reduction in inflammation.
Can it prevent or control diabetes?
There is some evidence that suggests that the Zone can be beneficial as it lowers inflammation in type-2 diabetics.
- A study was published in Obesity in 2006 that demonstrated although the weight loss was equivalent for type-2 diabetics on the Zone or a high-carbohydrate diet of equal calories, the subjects following the Zone Diet had statistically significant improvement in their levels of inflammation.
- The Joslin Diabetes Research Institute published ite dietary guidelines in 2007 for treating obesity, metabolic syndrome and diabetes. These dietary recommendations were essentially the same as the Zone Diet.
Finally, throughout the article, they continually refer to a “A review of the Zone diet published in 2003 in the Journal of the American College of Nutrition that concluded that scientific evidence ‘casts strong doubt’ on its health claims and theory.”
I sent them the following response (in red) that also seems to have fallen into the U.S. News and World Report wastebasket.
Apparently a “review” article was written more than a decade ago by a researcher employed by the U.S. Army that questioned the scientific validity of the Zone Diet (1). Since this review article was published in 2003, I will initially focus on the published peer-reviewed research available before 2003 that demonstrates the reviewer’s complete lack of any command of the available scientific literature that makes all of his conclusions totally invalid.
The author’s key point is “there are no peer-reviewed scientific data on the Zone Diet” (1). That is simply a false statement (2-5). Specifically, researchers at Harvard Medical School published a carefully controlled study demonstrating that a single meal following the composition of the Zone Diet dramatically altered the secretion of insulin and glucagon in a single meal as predicted (3). In addition, the subjects in that trial consuming the meal following the composition of the Zone Diet demonstrated significant reductions in their calorie consumption at the follow-up meal compared to consuming control meals of equal calorie intake. In 2000 the same Harvard investigators demonstrated that the Zone Diet had a similar effect on the reduction of appetite as well as a superior effect on resting energy expenditure compared to the control diet under hypocaloric conditions (4).
The author of that review also appears not to be familiar with other studies published more than a decade before his review that demonstrated hyperinsulinemia accelerates the activity of the enzyme delta-6 desaturase that converts dihomo-gamma linolenic acid into arachidonic acid (5,6). This increase in arachidonic acid would produce more “bad” eicosanoids, which is one of the fundamental themes of the Zone Diet. This published data more than a decade earlier rebuts the basic arguments of his “review”. The ignorance of this published information is difficult to understand since the references on the role of insulin and increased arachidonic acid formation were included in The Zone (7). Perhaps Mr. Cheuvront never read the book he was criticizing.
In addition, Mr. Cheuvront fails to mention that my book, The OmegaRx Zone, published in 2002, went into extraordinary detail on the role of omega-3 fatty acids to further alter eicosanoid levels (8). I should point out that the same book essentially launched the world-wide fish-oil revolution as it demonstrated the potential of high-dose fish oil to further alter eicosanoid levels in conjunction with the Zone Diet.
After Mr. Cheuvront’s review was published in 2003, it should again be noted that in 2007 the Joslin Diabetes Research Institute at Harvard Medical School published its dietary recommendations for treating obesity and type-2 diabetes (9). Those dietary recommendations are essentially identical to the macronutrient composition and caloric content of the Zone Diet. Joslin researchers confirmed the efficacy of those dietary recommendations with a clinical trial using the Zone Diet with type-2 diabetics (10). In addition, a significant number of carefully controlled articles have been published since 2002 that support the efficacy of the Zone Diet in treating metabolic disorders (11-16).
It is a sad commentary that I have to answer the “critique” of an individual who demonstrated a very limited understanding of the published scientific literature and the clinical trials that support the Zone Diet, but I hope this short overview addresses the obviously incorrect conclusions of his poorly researched “review” that is constantly referred to in the annual rankings.
The Zone Diet was developed to reduce inflammation. It is the only diet that has been consistently demonstrated to do so in clinical trials. I can only assume the reduction of inflammation is not considered an important benefit of the Zone Diet by the nutritional experts used by U.S. News and World Report.
Maybe some time in the future the editors and their “experts” may actually read the articles that I quoted to them. If they do, then they are likely to come to the same conclusion as the Joslin Diabetes Research Center that the Zone Diet is your best lifetime diet choice if the goal is to reduce inflammation.
- Cheuvront SN. “The Zone Diet phenomenon: A closer look at the science behind the claims.” J Amer College Nutr 22:9-17 (2003).
- Markovic TP, Campbell LV, Balasubramanian S, Jenkins AB, Fleury AC, Simons LA, and Chisholm DJ. “Beneficial effect on average lipid levels from energy restriction and fat loss in obese individuals with or without type 2 diabetes.” Diabetes Care 21: 695-700 (1998).
- Ludwig DS, Majzoub JA, Al-Zahrani A, Dallal GE, Blanco I, and Roberts SB. “High glycemic index foods, overeating, and obesity.” Pediatrics 103:E26 (1999).
- Agus MS, Swain JF, Larson CL, Eckert EA, and Ludwig DS. “Dietary composition and physiologic adaptations to energy restriction.” Am J Clin Nutr 71: 901-907 (2000).
- el Boustani S, Causse JE, Descomps B, Monnier L, Mendy F, and Crastes de Paulet A. “Direct in vivo characterization of delta 5 desaturase activity in humans by deuterium labeling: effect of insulin.” Metabolism 38:315-321 (1989).
- Pelikanova T, Kohout M, Base J, Stefka Z, Kovar J, Kazdova L, and Valek J. “Effect of acute hyperinsulinemia on fatty acid composition of serum lipids in non- insulin-dependent diabetics and healthy men.” Clin Chim Acta 203:329-337 (1991).
- Sears B. The Zone. Regan Books. New York, NY (1995).
- Sears B. The OmegaRx Zone. Regan Books. New York, NY (2002).
- Joslin Diabetes Reseach Center. www.joslin.org/docs/Nutrition_Guideline_Graded.pdf EPIC and Diabetes (2007).
- Hamdy O and Carver C. “The Why WAIT program: improving clinical outcomes through weight management in type 2 diabetes.” Curr Diab Rep 8: 413-420 (2008).