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Revisited by Jack Medina, M.A.

The bestselling book “The Zone”, by Barry Sears, Ph.D. presents a different approach to nutrition. The problem is verification of the author’s statements because no references were listed, and even though several good points were made, the book is filled with some gross inaccuracies.

What is the Zone?

It was never clearly defined. Try to figure it out for yourself from these excerpts: “The Zone is a real metabolic state that can be reached by everyone, and maintained indefinitely on a lifelong basis,” “Simply put, it’s the metabolic state in which the body works at peak efficiency. “The Zone is beyond wellness. The Zone is about optimal health.”

What is this supposed to mean? Is the body builder who is ripped with muscle at 250 pounds and 2% body fat and on steroids in the Zone? What about the person who chain- smokes, drinks beer and never gets ill and lives to a ripe old age – are they in the Zone? In other words, if you don’t define the Zone, how do you know when you are in it?

Claim #1: Dietary Fat Doesn’t Make You Fat!

Oh really! But this is what it says on page 20. And this isn’t all – there are other statements like “You have to eat fat to lose fat” and “The key to losing fat isn’t a matter of cutting calories, it’s a matter of reaching the Zone.” The first statement is entirely wrong and the second can only be verified if the Zone was clearly defined, which it isn’t. Furthermore, cutting calories does play an important role in fat loss, as does exercise. It is the law of Thermodynamics: energy in versus energy out. If you have more energy going out than you have coming in you are going to lose weight. There isn’t any other way!

Here are some facts to consider: not all calories are created equal. It takes more energy to metabolize calories consumed as protein versus those consumed as carbohydrates, and more to metabolize carbohydrate calories versus fat calories. A good study done in 1995 by Horton et al. supports the contention that the composition of calories clearly influences fat deposition. Numerous studies show that diets with a greater percentage of total calories from fat result in greater fat accumulation than one with less fat. In other words, if too much fat is consumed, it is more likely to be stored as fat. For most people it is much easier to overeat in fat calories since they tend to be less filling.

Claim #2: A Rise in Insulin Increases Body Fat!

If you read this book you would probably be convinced that insulin is the metabolic “bad guy” of the endocrine system. Sears suggests that a high-carbohydrate diet is harmful because it stimulates high insulin levels. Yet a rise in insulin doesn’t mean you automatically deposit carbohydrates you eat as fat.

Of course, if you overeat, excessive carbohydrates will be converted to fat, but so is excessive protein. Remember, it is much easier to deposit ingested fat as fat than it is to convert carbohydrates to fat. Converting carbohydrates to fat uses far more energy.

In addition, insulin is an extremely important anabolic (building) hormone with regard to skeletal muscle. In fact, a study by Pasquali et al. (1995) demonstrated that insulin may regulate levels of testosterone and sex-hormone-binding globulin in normal-weight and obese people.

High levels of insulin appears to be an important common denominator in obesity, heat disease, hypertension and Type II diabetes. However, for those who exercise regularly, this isn’t a problem; exercise has an insulin-like effect in transporting glucose from the blood into the cell. Athletes have an enhanced insulin sensitivity.

Claim #3: High-carbohydrate Diets Impair Athletic Performance?

This is ridiculous and goes against an avalanche of evidence supporting the role of carbohydrate intake and athletic performance. A high carbohydrate diet is essential for an endurance athlete’s performance. It is a well-supported fact that the amount of muscle glycogen is a limiting factor in prolonged endurance events. The idea that you should increase fat intake at the expense of carbohydrates is nonsense. Even the leanest of athletes usually has plenty of fat to begin with.

With regard to resistance exercise and short duration sports, a low carbohydrate diet could adversely affect performance, since carbohydrates are the primary fuel for intense work.

Calculating Food Intake Based on the Zone:

Getting to the bottom line, how much carbohydrate, protein and fat are you supposed to consume to reach the Zone? Apparently it is based upon your protein requirement, Sears is correct in recommending high meal frequencies (up to five meals per day) but the number of calories in this diet would convert a lot of people into emaciated rats. What does this mean? If you are interested in losing muscle mass, the Zone is for you.


Zone 1 – “Despite eating less fat, Americans are fatter than ever. Why? Because fat doesn’t make you fat, insulin does.”

WRONG! An abundance of research evidence demonstrates that fat calories and carbohydrate calories are processed differently. That is, it is easier to deposit excess fat as fat than to convert excess carbohydrates to fat. Excess calories is the key! Also, insulin doesn’t make you fat! Eating too much makes you fat. Besides, insulin is needed for protein synthesis and glycogen deposition, vital to all athletes.

Zone 2 – “Eating fat doesn’t make you fat, as long as it is the right type of fat (monosaturated).”

This statement is well supported scientifically. And yet, if you eat too much fat, regardless of what kind it is, you will get fat. Why not replace fat with a complex carbohydrate (fruits and vegetables, grains, legumes)? They are much more filling than fat and as a result you will be less likely to consume calories in excess of your energy needs. Americans get plenty of fat. The last thing they need is to be encouraged to eat more fat.

Zone 3 – “Athletes perform better on a high-fat diet.”

WRONG! This statement goes against the mass of scientific literature that supports the ergogenic effect of a high-carbohydrate diet in athletic performance, especially endurance athletes. Do you know which athletes might benefit from a high-fat diet? Sumo wrestlers and marathon swimmers!

Zone 4 – “Exercise alone will rarely overcome the negative effects of a high-carbohydrate diet.”

What negative effect is he talking about? Carbohydrate feedings before and during exercise have a positive ergogenic effect. A high-carbohydrate diet (not table sugar, cookies or cakes, but quality complex carbohydrates like fruits and vegetables, grains, legumes), is essential for athletic performance.

Zone 5 – “For Cardiovascular patients, a high-carbohydrate diet may be hazardous to their health.”

Certainly eating too much of anything wouldn’t be good for this population. But eating a complex carbohydrate diet with a fibrous vegetable and lean protein source would be healthiest for most athletes, as well as a cardiac patient.

Zone 6 – “Food may be the most powerful drug you’ll ever take.”

He might just be right about this! The two behaviors that could have the greatest impact on quality of life, health and happiness are eating and exercise.

Lastly, the book makes a generous point concerning eicosanoids and their important, if not vital, role in athletic performance, AIDS, skin disorders and more. At this point there is no evidence linking eicosanoid levels and the performance of muscle fibers or overall systemic exercise performance.

Until supporting evidence is available, the claims being made in this book are at best inconclusive. At worst, it is just another misleading diet.


Jose Antonio, Ph.D., earned his Master’s Degree in exercise physiology from Kent State University and his Doctorate in Cell Biology from the University of Texas Southwestern Medical Center.

Costill, D.L., Miller, J.M. Nutrition for endurance sport: carbohydrate and fluid balance. International Journal of Sportsmedicine 1:2-14, 1980.

Horton, T.J., Drougas, H., Brachey, A., Reed, G.W., Peters, J.C., Hill, J.O. Fat and carbohydrate overfeeding in humans: different effects on energy storage. American Journal of Clinical Nutrition 62:19-29, 1995.

Lemon, P.W.R. Do athletes need more dietary protein and amino acids? International Journal of Sports Nutrition 5:539-561, 1995.

Pasquali, R., et al. Insulin regulates testosterone and sex-hormone-binding globulin concentration in adult normal-weight and obese men. Journal of Clinical Endocrinology and Metabolism 80: 654-658, 1995.

Schutz, Y., Flatt, J.P.,Jequier, E. Failure of dietary fat intake to promote fat oxidation: a factor favoring the development of obesity. American Journal of Clinical Nutrition50: 307-314, 1989.

Schwarz, R.S., Ravussin, E., Massari, M., O’Connell, M., Robbins, D.C., The thermic effect of carbohydrat vs fat feeding in man. Metabolisn 34(3): 285-293, 1986.

Walberg-Rankin, J. Dietary carbohydrate as an ergogenic aid for prolonged and brief competitions in sport. International Journal of Sports Nutrition 5:S13-S28, 1995.

Author/speaker and an expert in ”Sports Performance Enhancement”. Jack Medina is available for speaking engagements, consultation and personal training of athletes in various sports, professional and amateur. Jack has written a new book, “The Winning Edge: Fueling & Training The Body For Peak Performance” with Dr. Roy Vartabedian, an internationally known New York Times Best Selling Author of the “Nutripoints” program for optimal nutrition. Both books are available online at Jack also has a monthly ezine (newsletter) available free which can be subscribed to on his website. All subscriber’s addresses will be confidential and not sold or given to any other organization or group.

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