When is a diet not a diet?

One of the major problems in nutrition is the lack of rigor in describing diets. The first problem is that the root of the word diet comes from the ancient Greek phrase “way of life”. A diet is not a short-term plan to fit into a swimsuit, but rather it is a way of life to reach a lifetime goal, like a longer and better life. If your goal is less grand like simply to lose weight, then to lose that weight and keep it off, you had better maintain that diet for the rest of your life. From that perspective, a diet like the Grapefruit diet doesn’t make much sense.

The second problem is the lack of precision in defining a diet. My definition of a diet is based on the macronutrient balance that ultimately determines hormonal responses. From this perspective, there are really only four diets based on the glycemic load, assuming that each diet contains the same number of calories.

Diet Common Name
Very low glycemic-load diet Ketogenic (i.e. Atkins diet)
Low glycemic-load diet Non-ketogenic (i.e. Zone Diet)
High glycemic-load diet American Heart (or Diabetes or Cancer, etc.) Association diet
Very high glycemic-load diet Strict vegetarian (i.e. Ornish diet)

Assuming these diets have an equal number of calories, you can then rank them in terms of the total amount of calories coming from protein, carbohydrates and fat as shown below:

Diet Macronutrient Composition
Very low glycemic-load diet 30% P, 10% C, and 60% F
Low glycemic-load diet 30% P, 40% C, and 30% F
High glycemic-load diet 15% P, 55% C, and 30% F
Very high glycemic-load diet 10% P, 80% C, and 10% F

You can see that depending on the macronutrient composition of the diet you choose to follow, it will generate very different hormonal responses. A ketogenic diet will induce increased cortisol levels that make you fat and keep you fat. High-glycemic diets induce excess insulin levels that make you fat and keep you fat. It’s only a low-glycemic diet that has been shown to burn fat faster (1) as well as maintain weight loss most effectively (2).

That’s why unless you define a diet carefully in terms of macronutrient balance, you can’t ever undertake any meaningful nutritional research to validate whether or not it achieves its stated goal. This is why most diet studies produce such conflicting results.

The wild card is which food ingredients you choose for a particular diet. This is where much of the confusion emerges as people throw around arbitrary terms like a Paleolithic diet or a Mediterranean diet. What the heck is a Mediterranean diet? Is it the diet from Morocco, Lebanon, Italy, or Spain? What you can do, however, is to review the food ingredients found in these diets.

For example, Paleolithic food ingredients would consist only of fruits, vegetables, nuts, grass-fed beef, eggs, and fish. A pretty limited group of foods to choose from, but it was all that was available to man 10,000 years ago. Mediterranean food ingredients include all of those in the Paleolithic group but now adding whole grains, alcohol, legumes, and dairy products. These were the dietary choices available about 2,000 years ago — a more diverse number of food choices for a particular diet, but now with a greater potential for generating inflammatory responses. Finally, there are the “Do-You-Feel-Lucky” food ingredients. This includes very recent additions to the human diet, such as sugar, refined carbohydrates and vegetable oils. These are food ingredients that make processed foods possible. However, they carry with them the greatest potential to increase cellular inflammation. Remember, it is increased cellular inflammation that makes you fat, sick, and dumb.

So if you want to be correct about the use of the word diet, then you should use the right terms. It could be an anti inflammatory diet using only Paleolithic food ingredients (i.e. a Paleo Zone Diet), or an anti inflammatory diet using only Mediterranean food ingredients (i.e. a Mediterranean Zone Diet), or even an anti inflammatory diet using the “Do-You-Feel-Lucky” food ingredients. This designation includes the most recent additions (sugar, refined carbohydrates, and vegetable oils) that have the greatest impact on inducing cellular inflammation, regardless of the macronutrient balance. Ultimately important are the hormonal responses of the macronutrient balance of the diet (especially after avoiding the worst offenders in the “Do-You-Feel-Lucky” group). The more restrictive your choices for food ingredients for any diet, the better the hormonal outcome for that particular diet. In particular, the primary clinical outcome for the anti inflammatory diet is the life-long management of cellular inflammation. And for that clinical parameter, the clinical research has found the anti inflammatory diet to be the clear winner regardless of the food ingredients selected (3-5).

References

  1. Layman DK, Evans EM, Erickson D, Seyler J, Weber J,; Bagshaw D, Griel A, Psota T, and Kris-Etherton P. “A moderate-protein diet produces sustained weight loss and long-term changes in body composition and blood lipids in obese adults.” J Nutr 139: 514-521 (2009)
  2. Larsen TM, Dalskov SM, van Baak M, Jebb SA, Papadaki A, Pfeiffer AF, Martinez JA, Handjieva-Darlenska T, Kunesova M, Pihlsgard M, Stender S; Holst C, Saris WH, and Astrup A. “Diets with high or low protein content and glycemic index for weight-loss maintenance.” N Engl J Med 363: 2102-2113 (2010)
  3. Pereira MA, Swain J, Goldfine AB, Rifai N, and Ludwig DS. “Effects of a low glycemic-load diet on resting energy expenditure and heart disease risk factors during weight loss.” JAMA 292: 2482-2490 (2004)
  4. Johnston CS, Tjonn SL, Swan PD, White A, Hutchins H, and Sears B. “Ketogenic low-carbohydrate diets have no metabolic advantage over nonketogenic low-carbohydrate diets.” Am J Clin Nutr 83: 1055-1061 (2006)
  5. Pittas AG, Roberts SB, Das SK, Gilhooly CH, Saltzman E, Golden J, Stark PC, and Greenberg AS. “The effects of the dietary glycemic load on type 2 diabetes risk factors during weight loss.” Obesity 14: 2200-2209 (2006)

Nothing contained in this blog is intended to be instructional for medial diagnosis or treatment. If you have a medical concern or issue, please consult your personal physician immediately.

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About Dr. Barry Sears

Dr. Barry Sears is a leading authority on the impact of the diet on hormonal response, genetic expression, and inflammation. A former research scientist at the Boston University School of Medicine and the Massachusetts Institute of Technology, Dr. Sears has dedicated his research efforts over the past 30 years to the study of lipids. He has published more than 30 scientific articles and holds 13 U.S. patents in the areas of intravenous drug delivery systems and hormonal regulation for the treatment of cardiovascular disease. He has also written 13 books, including the New York Times #1 best-seller "The Zone". These books have sold more than 5 million copies in the U.S. and have been translated into 22 different languages.

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