In Barry Sears' Mastering the Zone, we see again that calories do not count but protein does. Sears states that carbohydrates stimulate the release of insulin* which affects eicosanoids but neglects to tell you that protein also elicits an insulin response.

An eicosanoid is a hormone that among other functions helps regulate inflammation, the blood's tendency to clot and the immune system. Bad eicosanoids are the result of insulin release according to Sears' book. No research exists to support Sears' proposed relationship between performance, fatness, diet, insulin, bad eicosanoids and disease.

One advantage to this type of diet is that the carbohydrate recommendations are higher than Atkins' plan. The typical American diet is not far from the recommended 40/30/30 ratio of carbohydrate/protein/and fat and may be ideal for certain individuals. However, just like the Atkins diet, the Zone removes carbohydrates to achieve the lower caloric intake necessary to promote weight loss.

The Downside

The concept is the same as other high-protein diets but less aggressive and the smoke screen differs. Although the suggested foods are healthier than the typical American diet and fall into a percentage they normally eat, the science is incorrect and used to disguise the low-calorie recommendations. Because calories are based on protein requirements, the number of calories that the average female consumes on this food plan is approximately 975. For the average male, meanwhile, the amount is 1,700 calories. Based on the first law of thermodynamics, at this caloric intake, weight loss is guaranteed no matter what you consume. However, due to the very low calories, long-term success would be very challenging, and there is no such thing as a "one size fits all" diet as the author claims.

*It takes more than insulin to store fat. Insulin is a complex hormone with myriad life giving functions and is only a mechanism that is used in the accumulation of fat stores when a person supplies the calories. The hormone does not cause the body to continually accrue fat unless a person regularly eats too much. Since humans can not live 5 minutes without insulin we must learn to live without eating in excess and then looking for something else to blame it on.