Developed by Barry Sears, Ph.D, the Zone Diet emphasizes eating a balanced ratio of carbohydrates, protein and fat. The "zone" refers to the optimal mental and physical state of athletes in peak performance. Dr. Sears believes that a diet consisting of 40 percent carbohydrates, 30 percent protein and 30 percent fat can help you lose weight, optimize physical and mental capacity, and prevent onset of cardiovascular disease, cancer and diabetes.
History
In the 1970s, after his father died of a heart attack at the age of 53, biochemist Dr. Sears began researching how fats affect cardiovascular health.
In 1982, the Nobel prize in medicine went to three researchers for their discoveries related to eicosanoids, which control the body's hormones. This led Dr. Sears to pursue how diet affects your production of eicosanoids, particularly through the secretion of insulin and glucagon.
In 1995, he published "Enter the Zone," which has reportedly sold more than 3 million copies. He has since written at least 10 other books about the Zone Diet.
Principles
The Zone Diet focuses on managing insulin and glucagon levels to maintain the balance of eicosanoids. The pancreas secretes insulin to store blood sugar and glucagon to release it.
Dr. Sears claims that taking in carbohydrates triggers insulin production and eating proteins stimulates the release of glucagon. A high-carbohydrate, low-protein meal of pasta, for instance, causes high production of insulin and low production of glucagon, which means blood sugar drops because it cannot be released into the bloodstream.
Effects
Eicosanoids, or what Dr. Sears calls the "body's superhormones," can be "good" or "bad," he says. "Good" eicosanoids are anti-inflammatory and anti-coagulant, while "bad" ones have the opposite effect. Dr. Sears' theory is that your body determines which ones to produce based on your intake of carbohydrates and proteins -- and the resulting amount of insulin and glucagon in your blood cells.
Features
The Zone Diet encourages low-fat proteins; monounsaturated fats found in olive oil and avocados; and foods rich in fatty acids, which help produce "good" eicosanoids. These include gamma linolenic acid, found in oatmeal, and eicosapentaenoic acid, found in fish.
Foods to avoid on the Zone Diet include refined carbohydrates, simple sugars, foods with saturated fats, such as red meat and whole-fat dairy; and fruits, vegetables and grains with a high glycemic index, such as rice, papaya, mango, corn, potatoes and carrots.
Considerations
Opinions vary on the effectiveness on the Zone Diet. The American Heart Association repudiates the Zone Diet because of its high protein and lack of fiber. Bodybuilding.com points out that low levels of carbohydrates may result in lower endurance for athletes.
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