In 1995, Dr. Barry Sears, a biochemist, introduced the Zone Diet when he published his book, The Zone: A Dietary Road Map. While advocating a fixed ratio of carbohydrates, proteins, and fat as so many other diets do, the Zone addresses hormone levels, including insulin, and the inflammatory influence of the foods eaten. When insulin levels are at optimum level and inflammation is held at bay, the dieter is said to be in the ideal zone for robust health.
As with all popular diets, the Zone has many fans but plenty of critics, too.
Sears recommends a ratio of 40% carbohydrates, 30% protein, and 30% fat consumption on a daily basis. He says this ratio of macronutrients is necessary to maintain optimum hormonal balance.
Critics say this is too much protein and fat but Sears maintains the body needs them both to eliminate hunger pangs. This diet contributes to a feeling of satiety and slows down digestion of carbohydrates. The slower carbohydrate digestion produces lower, steadier insulin levels that, in turn, means fewer excess calories are stored as body fat and fat already stored is more readily burned as fuel.
Also, when insulin levels get too high, glucose levels drop, thereby robbing the brain of its key nutrient. When glucose levels in the brain drop, it gets hungry, sluggish, and metabolism slows. All these starving brain reactions rev up the appetite and cause cravings even though the cravings are usually for nutrient-poor foods, such as sweets and starchy carbohydrates. When the starving dieter turns to these non-nutritious quick fixes, the cycle begins anew.
Foods have inflammatory or anti-inflammatory properties that contribute to overall wellness. Numerous medical studies indicate it’s the overall inflammatory level in the body that contributes to or possibly even triggers the onset of many chronic medical conditions, including diabetes, cardiovascular disease, arthritis, and age-related dementia.
Sears says eating foods in the Zone Diet’s ratio reduces systemic inflammation by releasing chemicals called eicosanoids, which are chemically similar to aspirin but without the gastric bleeding so often associated with aspirin-based anti-inflammatory medications.
To put this biochemistry data into dieter-friendly terms, Sears suggests keeping daily protein intake in check by using the palm of the hand as a guide. Total daily intake of protein-based foods should be no larger than that.
Eat as many vitamin-rich non-starchy, raw vegetables as possible and enough complex carbohydrates (whole-grain breads and pastas, minimally processed grains, and potatoes) to produce enough glucose to keep the brain functioning at maximum capacity.
Sears advocates consuming 30% of daily caloric intake as fats so don’t shy away from them but limit them to lean meats, fish, and monounsaturated oils, such as olive oil, omega-3, and omega-6 fatty acids. These healthful fats will supply the nutrients only they contain and slow digestion to prolong feelings of fullness between meals.
In some much-publicized studies, followers of the Zone Diet have been able to add muscle mass while reducing body fat more quickly than study participants following different diets. Some of it’s biggest fans say the Zone Diet calls for so much nutrient-rich, low-calorie foods they have trouble eating enough of it to get all the day’s required calories.