The Zone Diet was first introduced in 1995 by biochemist Barry Sears. It is based on eating a diet consisting of 30% protein, 30% fat, and 40% carbohydrates. The goal of the diet is to keep you in "The Zone", Sears' term for proper hormone (insulin) balance. Insulin helps regulate the storage of fat. High-carbohydrate meals trigger insulin release, which causes your body to store food as fat. Eating in "The Zone" maintains stable insulin levels which means less stored fat and more efficient fat burning.
In addition to weight loss, Sears contends that eating The Zone Diet can help prevent diabetes, high blood pressure, and heart disease, along with improving athletic performance. He believes that what is thought of as "good nutrition" -- a high carbohydrates, low protein, and fats diet - is "dead wrong." By eating in "The Zone" you produce a "metabolic state in which the body works at peak efficiency,"
What Do You Eat? The diet focuses on achieving the 40/30/30 ratios. You don't necessarily reduce calories, you just just eat them in different ratios. Sears describes a Zone meal as follows: "Eat as much protein as the palm of your hand, as much non-starchy raw vegetables as you can stand for the vitamins, enough carbohydrates to maintain mental clarity because the brain runs on glucose, and enough monounsaturated oils to keep feelings of hunger away."
You’ll be eating three meals and two snacks each day, spread throughout the day to keep your blood sugar levels constant. Lean protein sources (chicken, turkey, fish, pork, veal, egg whites) are included in each meal and snack. Protein sources high in fat, including organ meats and red meats should be avoided.
Carbs are broken up into "Favorable" such as most vegetables and lentils, beans, whole grains, and most fruits. "Unfavorable" carbs consist of such foods as pasta, banana, bread, carrots, brown rice, dry breakfast cereal, and all fruit juices. The "Favorable" carbs portions should be twice the size of the protein portion. A much smaller portion is allotted for the "unfavorable" carbs, which are restricted because they release glucose quickly resulting in an insulin spike....something you're trying to avoid on the Zone Diet.
The diet keeps saturated fats to a minimum but includes, almonds, olives, olive oil, canola, macadamia nuts, and avocados. Dairy foods allowed are 2% fat milk, 2% fat natural yogurt or Greek yogurt, low fat cheese and 2% fat cottage cheese. Egg whites are preferred to whole eggs.
Reviews There are some mixed reviews on the Zone Diet from nutrition experts. The Center for Science in the Public Interest lists it on it’s acceptable list. Consumer Reports recently rated it 4th, behind Jenny Craig, Slim-Fast, and Weight Watchers, but ahead of Ornish, Atkins, and Nutrisystem. The diet itself comes under minimal criticism, it’s the science it’s based on that gets the most skepticism. Some believe that Sears has distorted or exaggerated the meaning of some of the basic research for the book. There is also some debate on whether the diet should be considered "low carb". The Dietary Guidelines for Americans from the USDA suggest a range of 45-65% carbs. The Zone recommends a 40% carb level.
Bottom Line The Zone Diet is fairly easy to follow, seems to be well tolerated, and has been shown to be effective. The key questions you need to ask with any diet is, can I eat like this forever? Would I enjoy eating like this? If eating in the "Zone" looks like it’s something you can handle, it could be worthwhile to try.