The Zone Diet plan came into the diet world many years ago, just under a different name (40-30-30). Dr. Barry Sears a few years ago, was the author of a book called "Enter the Zone", which used this method of counting calories for specific food groups to lose weight, plus reduce blood pressure levels.
This diet requires people to eat their daily calories in a very specific proportion at each and every meal which proves very difficult, unless you buy the Zone Bars, a special blend of scientifically produced bars designed to help you lose weight on the Zone Diet.
The success of the Zone Bars and also the Zone program was simply because of the difficulty that you will have in trying to prepare a variety of meals using 40 percent of your calories from carbohydrates, 30 percent from protein, and 30 percent from fat calories.
The high cost of these meals and bars, or simply the difficulty in preparing your own meals, would make this method of dieting an instant failure for most dieters.
I personally would not recommend this method of dieting as there are more effective and beneficial methods of weight loss, such as healthy eating and exercise.
As with the same for many diets, science and medical research will show many alarming side effects and problems with the Zone Diet, namely the higher risk of heart disease.