The Zone Diet

The Zone Diet: How It Works

The Zone diet’s eating plan is a combination of a small amount of low-fat protein at every meal, fats, and carbohydrates in the form of fiber-rich vegetables and fruits. The plan establishes a ratio for which Sears contends the body is genetically programmed (that 40-30-30 figure). And yes, we’ll be thinner to boot.

Sears claims that the Zone diet is based on his 15 years of research in bio nutrition. Although the book is full of success stories, including those of elite athletes, research that validates his specific claims isn’t there. That doesn’t mean that Sears’ theories are wrong; it’s just that no scientific evidence has proven that his program works.

Sears bases his theory on using diet to control the body’s production of the hormone insulin. Among insulin’s many roles, it helps regulate storage of excess energy as fat. The goal is to keep a balance between fat-storing insulin and the hormone glucagon, insulin’s opposite, whose job it is to release the stored glucose from the liver when it is needed. Maintaining the correct balance between the two is accomplished by watching the size and specific content of your meals. In other words, you must be mindful of what you put on your plate. Sears suggests that we think of food not as “a source of calories but as a control system for hormones.”

The Zone Diet: What the Experts Say

The Zone diet draws mixed reviews from nutrition experts. Researchers at the Center for Science in the Public Interest, which rated several fad diets, recently put it on their acceptable list, unlike Dr. Atkins’ New Diet Revolution, Sugar Busters!, The Carbohydrate Addict’s Diet, and Protein Power. “If you ignore the scientific rhetoric, the diet isn’t bad,” says Bonnie Liebman, MS, nutrition director for the center’s publication, Nutrition Action Healthletter. As a caveat, she points out the diet restricts carbohydrates more than necessary. “You are getting carbohydrates from fruit and vegetables on the diet, but a lot of the science is bunk,” she says. What she likes is that the diet is relatively easy to follow: “You have a piece of protein the size of your palm, and you fill the rest of your plate up with fruits and vegetables.”

Susan Roberts, PhD, head of the Weight Regulation Program at Tufts University and a professor of medicine and psychiatry there, also gives The Zone a qualified thumbs up. “Like most fad diet books, The Zone diet takes one of the several known controllers of energy, blood glucose, and blows it up into a whole book,” she says. “It downplays the other factors that also determine how hungry we get and how much we eat, such as fiber and the caloric density of the food.”

Roberts also finds fault with some of The Zone diet’s food recommendations, such as that high-fat ice cream. Sears says it’s OK, because it won’t raise your blood sugar precipitously, but it’s not OK for other reasons, Roberts notes, such as the fact that the cream in the ice cream is saturated fat, which isn’t good for your overall cholesterol. (To be fair to the diet, Sears only allows a half-cup and certainly doesn’t suggest you make it a habit.) Yet Roberts likes the amount of vegetables and legumes recommended, and so, she says, “My personal rating for The Zone would be three stars out of five.”

Other nutritional experts, including some of Sears’ former colleagues, are critical of his conclusions from the scientific evidence, contending that he has distorted or exaggerated the meaning of much of the basic research. They point out that no direct studies to verify his conclusions have been performed.

The Zone Diet: Food For Thought

The 40-30-30 ratio of the Zone diet applies to all meals all the time, and a broad range of foods are allowed, so there are no confusing schedules or conditions that need to be memorized. Though dieters should find it easy to follow, nutritionists give the Zone diet mixed reviews.

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