Dr. Sear's Zone Diet

The Zone diet was developed and popularized by a biochemist, Barry Sears, Ph.D. It is based on the premise that achieving "hormonal balance" through eating ideal balances of carbohydrates, proteins, and fats at every meal and snack, is the most effective way to help the body digest and utilize ingested foods. Barry Sears refers to this proposed optimal functioning as being "in the Zone" and hence the name "Zone diet."

By its recommended food intake, the Zone diet is generally considered a low-carbohydrate, high-protein diet. The diet is viewed in this light as it promotes the intake of 40% carbohydrate (as against the Dietary Guidelines for Americans recommendation of 55%), 30% protein (with 15% being the regular recommendation), and 30% fat (being the standard recommendation of the American Heart Association – AHA). It is therefore known as the 40-30-30 diet plan. Nonetheless, it is not as restrictive in total amount of carbohydrate intake as other low-carbohydrate diets like the Atkins diet.

Sears explains that being "in the zone" boosts energy levels with significant improvements in both physical and mental performances and also helps delay signs of aging. Ultimately, Sears says that the Zone diet helps to prevent chronic cardiovascular diseases while promoting effective and long-term fat burning.

How the Zone Diet Works

The core of the premise behind the Zone diet and why it works according to Dr. Sears is the interplay of foods, the hormones insulin and glucagon, and certain hormone-like compounds known as eicosanoids.

Sears believes that when blood glucose levels abnormally increases due to excessive consumption of high-glycemic index carbohydrate-containing foods, that the cells in the pancreas release the hormone, insulin. Insulin is a hormone that is known to signal cells in the body to absorb any excess glucose from the bloodstream and store it as either glycogen in liver and muscle cells or as fat in fat cells (adipose tissues).

Conversely, when the blood glucose levels go down, different cells in the pancreas release the hormone known as glucagon. Unlike insulin, glucagon gives a counteracting instruction to liver and muscle cells to release their stored glycogen (comprised of 75% water and glucose) instead and convert same back into glucose which is subsequently burned for energy by the body. If glucose levels continue to remain significantly low, the body ultimately turns to burning it fat stores in fat cells (adipose tissues) for energy.

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Biochemically, Sears theorizes that carbohydrates stimulate the production of insulin and proteins stimulate the production of glucagon. Thus the interplay between these two hormones and the type of food intake that triggers their secretion by the body plays a significant science behind Dr. Sears’ Zone diet.

The Zone diet therefore suggests that dieters need to eat the right ratio of carbohydrates to proteins and fats in order to be able to effectively regulate their blood insulin levels and therefore reduce the body’s propensity to store glucose as fat in the body.

Determining the 40:30:30 Ratios

This diet is a highly structured one as dieters are specifically instructed to make sure that they maintain the 40%-carbohydrates, 30%-protein, and 30%-fats ratios at every meal and snack they have.

On a positive note, the Zone diet appears to take into cognizance the fact that daily calorie intake on any diet should not be a one-fit-all but should rather be based on the dieter’s unique body type and physiology.

To achieve this, the diet bases the amount of food to be consumed to be relative to the dieter’s protein needs. An individual’s protein is calculated based on the person’s height, weight, hip and waist measurements as well as activity level.

Consequently, the result from the individual’s protein needs can now be effectively used to determine the amount of carbohydrates and fats to be allowed on the diet in order to maintain the "equilibrium" in the body’s hormonal secretion. Usually the result of this calculation is a daily diet that ranges from about 1,100 to 1,700 calories.

Foods in The Zone diet

The Zone diet categorizes foods as either "good" or "bad" and the dieter must therefore ensure that each meal of the day comes from the "good" foods in making up the 40-30-30 macronutrient ratio of the diet.

Good sources of carbohydrate allowed in the Zone diet include small amounts of grains, non-starchy vegetables, oatmeal, barley, and some fruits. Carbohydrates to be consumed should be natural, complex, and unrefined.

Some of the proteins that are considered "good" by the diet include lean chicken, turkey, and other poultry as well as seafood, and egg whites.

Fats that are allowed are small amounts of canola and olive oil, as well as low-fat/non-fat dairy products. There is a general recommendation by Dr. Sears that all dieters using the Zone diet should use specific ratios of Omega-3 to Omega-6 fatty acids. In fact many people attribute the popularity of pharmaceutical-grade Omega-3 fish oils to Dr. Sears.

Including enough monosaturated fatty oils in a meal not only help to make the dieter feel fuller for longer periods but also reduce the absorption rate of carbohydrates into the bloodstream.

However, the following types of "bad" foods – according to the Zone diet – are strictly forbidden: red meat or fatty meats; whole milk dairy products; bread, rice, cereals and most baked foods; egg yolks and potatoes; certain fruits and vegetables such as carrots, bananas, papaya, mangos, corn, as well as fruit juices in general and many other fruits. All refined carbohydrates are specifically forbidden.

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Essentially, the Zone diet recommends that 40% of the calories in every meal or snack should come from natural and complex carbohydrates, 30% from lean protein sources, while the balance 30% from healthy unsaturated dietary fats.

Interesting and unlike most other diets, the Zone diet is more concerned about people reducing body fat than reaching a particular weight. The diet’s aim is for men to have only 15% body fat while women to have a 22% body fat.

However, one issue that obviously comes to mind is that of how to get the ratios of the Carbohydrate-Protein-Fat macronutrients right in order to start the diet. For most individuals, the measuring and calculating involved could become a little daunting, time consuming and to say the least confusing when just starting out.

Like most other low-carbohydrate diets, the Zone diet has equally met with its fair share of criticism from dietitians and nutritionists alike. Although they are favorably disposed to the 30% fat recommendation of the diet, they however consider the 30% protein as significantly high and the 40% carbohydrate as being low. Also, other experts are of the opinion that the Zone diet’s theory on insulin is flawed as they argue that there is yet no substantial scientific proof to verify the role insulin plays in weight regulation.

Nonetheless, most a-list celebrities who are known to use the Zone diet can swear by the results they’ve achieved. This is why the Zone diet is often regarded as a "Celebrity Diet". But then, some health experts as well as the celebrities are of the opinion that the Zone diet’s recommendations do not stray too far from the federal health guidelines in the Dietary Guidelines for Americans and have therefore strong advocates of the Zone diet.

The popularity of the Zone diet has also grown because many restaurants have included Zone diet meals in their menu. Also, the company has developed a program of home-delivered Zone meals for those who don’t have the time to prepare their meals themselves or who are having difficulties preparing them.