The Zone Diet was developed in the late 1990s by Dr. Barry Sears, a biochemist who published his nutritional ideas in a bestselling diet book. Sears claims his formula for balancing intake at every meal stabilizes insulin levels and avoids fat storage. The diet is low to moderate in carbohydrates and works on the theory that insulin spikes caused by high-glycemic foods result in weight gain. It can be complex to select from foods allowed on the plan, but it's highly publicized use by Hollywood celebrities has ensured its enduring appeal.
The Formula
The diet has an eating formula of 40 percent carbohydrates, 30 percent protein and 30 percent fat at each meal. Calories are severely restricted -- 500 calories per meal is the maximum allowed. Even with modest snacks, the diet may not supply sufficient fuel, particularly for active people. The Zone has been criticized for a lack of scientific rigor. There are no published studies supporting the diet and Northwestern University Feinberg School of Medicine has criticized its low fiber, complicated food choices and low intake of vitamins D and E and minerals iron, calcium and magnesium.
Zone Carbs
Carbohydrate intake at 40 percent per meal is lower on the Zone Diet than a typical daily intake of 50 percent to 60 percent, but higher than some very restrictive low-carb diets like Atkins. Dieters are allowed to choose carbohydrates like most whole grains, lentils, beans, most vegetables such as green beans, broccoli, spinach and artichokes, and fruits like apples, grapes strawberries and tangerines. "Unfavorable" carbs include pasta, most breakfast cereals and breads, fruit juices, bananas, carrots, potatoes and rice. While unfavorable carbs are not forbidden, they are strongly discouraged and dieters are urged to consume very small portions of them.
Zone Protein
Protein on the Zone Diet -- 30 percent of each meal -- focuses on lean poultry, fish high in omega-3 fatty acids like salmon, egg whites and some tree nuts. Red meat and organ meats are discouraged due to their high saturated fat content. The protein level consumed on the diet is higher than the typical American protein intake, according to Northwestern University School of Medicine. And, the University of Massachusetts Center for Nutrition in Sport and Human Performance says that only 10 percent to 15 percent of daily nutrition should come from protein on a balanced diet. More than that, and you may experience calcium loss and bone loss as the body attempts to digest excess protein. Columbia University Health Systems points out that digesting protein draws water from the body's stores and that much of the weight loss on the diet may be attributed to water loss.
Zone Fats
On the Zone Diet, 30 percent of each plate is devoted to fats that include low-fat milk, yogurt and cheese, extra-virgin olive oil, the fats from lean meats and coldwater fish, avocado and small amounts of fatty meats like Canadian bacon. Chips and other fat-laden snacks, most commercial baked goods and high-fat dairy are on the "unfavorable" list. While the fat choices encouraged by the diet are healthy ones, Northwestern School of Medicine points out that the level of fat in the diet is higher than that recommended by most leading health organizations.
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