Zone Diet Review

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The Zone diet, developed by Barry Sears, Ph. D., is a low carbohydrate, high protein diet. The diet is based on the principles of dieters eating an ideal balance of carbohydrates, proteins and fat at meals and snacks that balance hormones and keep insulin levels stable. When insulin levels are kept stable, people should enjoy the benefits of losing pounds as well as other health benefits. There are, however, some drawbacks with the Zone diet, according to health experts.

History of the Zone Diet

Sears is a former research scientist from the Boston University School of Medicine and the Massachusetts Institute of Technology. After his father’s premature death from a heart attack at 53 years old, Sears began researching the role of fats in the development of cardiovascular disease. Sears’ book, Enter the Zone, became a bestseller in 1995.

Zone Diet Principles

The Zone diet is designed to promote weight and fat loss, but there are also claims that it improves health. The diet is very structured. Each meal consists of 40 percent carbohydrates, 30 percent protein and 30 percent fats. This combination is what Sears says is the ideal ratio of protein to carbohydrates, which says Sears, allows the body to function at its optimum best. When people eat this combination of protein, carbohydrates and fat they should feel more energy, be able to delay the sings of aging and prevent chronic diseases. People should also feel better emotionally too.

The Zone diet principles are based more on body fat than numbers on a scale. Men should aim for a body fat percentage of 15 percent, and women should aim for 22 percent body fat.

The amount of food a dieter eats is based on his or her protein requirements. Protein intake is calculated by height, weight, waist measurements and activity levels. When people go on the Zone diet, they typically consume about 1,100 to 1,700 calories a day.

Portions of meals are simplified into Zone Food Blocks, so instead of eating a specific number of calories, dieters eat a specific number Zone Blocks in the necessary proportions.  Foods are either defined as good or bad. Some of the “good” foods are the following:

  • lean chicken and other poultry
  • seafood
  • egg whites
  • low-fat, non-fat dairy
  • canola oil
  • olive oil

Some “bad” foods include the following:

  • red meat
  • egg yolks
  • Some vegetables such as carrots and corn
  • Most fruit juices and fruits such as raisins, bananas, papayas and mangoes
  • Most baked goods such as bread, cereal, bagels and rice
  • caffeinated coffee
  • diet sodas
  • alcohol

Drawbacks of the Zone Diet

Getting the portions correct requires a lot of measuring and calculating, which can be a bit tedious and time consuming when people first begin the diet. Other rules include eating three meals and two snacks every day, eating the first meal within one hour after waking up, not allowing more than five hours between meals and drinking more than 8 cups of water each day.

The Zone diet also does not conform to the recommendations of the Dietary Guidelines for Americans, which state that people should get 55 percent of their calories from carbohydrates, 15 percent from protein and no more than 30 percent from fats. These recommendations also suggest people consume more whole grain products, which are limited on the Zone diet.

A review of the Zone diet that was published in the Journal of the American College of Nutrition in 2003 argued that even though it is well documented that carbohydrates increase the production of insulin and proteins stimulate the production of glucagon, these conditions only happen when single nutrients are eaten. Mixed combinations make the situation more complex and Sear’s conclusions are too simplistic.

In addition, the claims that the Zone diet allows people to perform at peak physical levels is refuted by several studies done by sports nutritionists who argue limiting carbohydrates can affect athletic performance.

Risks of the Zone Diet

While Sears states there are few or no side effects associated with the diet, several nutritional experts do not agree and argue there may be some risks. Since the Zone diet requires carbohydrate consumption below the nutritional daily requirements, the deficiency may lead to several health risks such as cardiac problems, orthostatic hypotension (temporary low blood pressure) and ketosis. Dieters may also suffer from mineral and vitamin deficiencies, added stress on kidneys, higher increase in the risk of gout, osteoporisis, kidney stones and kidney damage (Paradise).


Davidson, Tish, A.M. “Zone Diet.” The Gale Encyclopedia of Diets. Ed. Jacqueline L. Longe. Detroit: Gale, 2008. 2 vols.

Paradise, Lee Ann. “The Zone Diet.” The Gale Encyclopedia of Alternative Medicine. Ed. Laurie Fundukian. 3rd ed. Detroit: Gale, 2009. 4 vols.

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