In 1995, HarperCollins published a diet book entitled The Zone: A Dietary Road Map by Dr. Barry Sears. Dr. Sears is not a medical doctor, or even a nutritionist, but a former researcher in biotechnology at Massachusetts Institutes of Technology. The diet is based upon five principles mapped out on the website www.zonediet.com which are: 1. following the diet, 2. omega-3 fish oil intake, 3. the importance of polyphenols, 4. fitness, and 5. targeted supplements. While the diet is intended to help you shed weight it more importantly purports to help the body burn fat more efficiently. The purpose of the diet is also about improving overall long term health. The diet emphasizes eating low-fat proteins (like chicken breast or skinless turkey breast, egg whites, most seafood, mushrooms, and soy products), low glycemic carbs, and healthy unsaturated fats. The diet is based upon a 30/30/40 formula. Every meal and snack is supposed to be proportioned to contain 30% protein, 30% fat and 40% carbohydrates. As far as fitness, Dr. Sears recommends 30 minutes of fitness six times a week for overall cardiovascular health.
Carbohydrates that you are encouraged to eat are primarily fruits and vegetables. A smaller amount of carbohydrates is to be eaten if you have chosen “unfavorable” ones — these include brown rice, pasta, papaya, mango, banana, dry breakfast cereal, bread, bagel, tortilla, carrots, sweet potatoes, and all fruit juices. The diet generally discourages eating chips, sweets, and junk foods. As far as dairy products egg whites are preferred over whole eggs and low/no fat cheese and milk are advocated. For your 30% of healthy fats suggested sources are olive and canola oil, macadamia nuts, and avocados. Dr. Sears notes that you should eat three meals and two snack per day all consisting of the 30/30/40 portion and you should never go longer than five hours without eating. Meals should be approximately 500 calories and snacks approximately 100, although calorie counting is not emphasized or required for this diet, it’s just a rule of thumb. Your sex, age and weight among other factors will ultimately determine the caloric and protein intake you need. Since the popularity of the diet book the brand has expanded to sell food and supplement products such as zone bars, shakes, protein powder, fish oil supplements, and antioxidant supplements.
The criticism of the food suggested for the plan is not as harsh as the scientific claims that Dr. Sears makes throughout the books. Dr. Sears believes, based on his 15 years of research, that excessive complex carbohydrates causes obesity by increasing insulin output and thus fat storage. Eiconsanoids are hormones that regulate inflammation in the body and Dr. Sears believes that excess insulin leads to an imbalance of these eiconsanoids. He theorizes that in turn this results in heart disease, cancer, and arthritis among other undesirable health effects. I use the term theorize because although no one has outright said these theories are incorrect, they have not been proven in any type of clinical setting or in any long term study. Thus, those who criticize the program the most point out that the portions of the book (which is a significant portion) that offers these scientific explanations for how the zone physiologically works have not been proven. Additionally, he does not mention the factor of emotional eating which is a major reason for weight issues in our society. The American Heart Association doesn’t recommend the diet because of the long term health effects and lack of research that has been done on them. The diet is considered a high protein diet and is often lumped together with The Atkins Diet and The South Beach Diet, although it is less restrictive than the Atkins.
Another large criticism of the diet is that it is inappropriate for vegetarians and vegans and does not emphasize the need and benefits of a plant based diet. For this reason, Dr. Sears published The Soy Zone in 2000 which is more vegetarian friendly.
The diet has been endorsed by or linked to several large celebrities including Jennifer Aniston, Renee Zellweger, Cindy Crawford, Charlie Sheen, Tiger Woods and Tom Cruise. In fact, the former “fattest man in the world” Mexican Manuel Uribe who once weighed in at 1,235 pounds lost 397 pounds on the zone diet. He largely credits the zone as being the only diet he has ever been able to successfully follow. A PBS documentary show called “Scientific American Frontiers” compared many popular diets and participants that followed the diets for a specific length of time. Interestingly enough, the most fat loss and the most muscle gain resulted from the participants on the zone diet. They also reported the diet as the easiest regimen to adjust to with the least amount of fatigue and hunger reported.
An exert from the book itself can best explain the underlying message of Dr. Sears and his diet plan “Eat as much protein as the palm of your hand, as much non-starchy raw vegetables as you can stand for the vitamins, enough carbohydrates to maintain mental clarity because the brain runs on glucose, and enough monounsaturated oils to keep feelings of hunger away.”