With the different types of diets in the news, on websites and at the water cooler, it's easy to lose track of what kind of diet works best for whom and why. If you want to choose a good eating plan for your health and lifestyle, it's best to compare the overall approach and requirements of diets before selecting one to follow. Two popular diets, Dr. Sears' Zone Diet and a calorie restricted diet, present some important contrasts.
Histories
Biochemist Barry Sears published The Zone in 1995. Sears developed his best-selling diet plan based on theories about hormonal balances and how they are affected by the ratio of nutrients we consume. Restricting calories can be a more general approach. Limiting calorie intake has long been a common way to lose weight, especially when combined with regular physical activity. Calorie restriction is a recent, more formal approach to adhering to a reduced calorie diet.
Theories of the Zone
Sears suggests that the distribution of nutrients that puts dieters in a fat-burning, hormonally balanced "Zone" is 40 percent carbohydrates, 30 percent protein and 30 percent fat. Insulin-resistance is thought to be a problem with many overweight people because insulin secretions are involved in the processing of carbohydrates. Sugars and grains in excess of 40 percent of the daily intake called for by The Zone are suspected to cause imbalance with insulin production and trigger inflammatory responses in the cells of some people.
Theories of Calorie Restriction
Eating the minimum amount of calories to provide all the essential nutrients that a body requires is a key tenet of calorie restriction. The Calorie Restriction Society supports a diet in which the intake of calories is "safely reduced by as much as 10 percent to 40 percent below the amount of energy that the body would tend to naturally desire." "Scientific Psychic" offers science-based resources that cite numerous studies as far back as the 1930s in which the lifespans of mice and other organisms have been increased by enforcing calorie restriction, as opposed to allowing free eating.
Features and Comparisons
When following the Zone Diet, increased protein intake tends to slow digestion and may reduce hunger signals. This is claimed as one positive effect of being in the Zone Diet's 40-30-30 nutrient balance. That same ratio of nutrients is sometimes a goal of the calorie-restricted dieter. Calorie restriction as a formal practice requires further calculations based on a formula which uses age, weight, gender and activity level to determine your level of restriction. Calories are not restricted in Sears' Zone Diet. However, as Tara Parker-Pope writes in a Feb. 25, 2009, "New York Times" article, "Study Zeroes In on Calories, Not Diet, for Loss," research shows that cutting carbohydrates naturally cuts calories from most diets, adding to weight loss potential.
Expert Insight
The American Dietetic Association recommends reducing calories to lose weight and also calls for a diet that emphasizes produce and low-fat dairy, which are generally low-calorie choices. Twenty years of calorie restriction among primates being studied at University of Wisconsin might mean longer life with fewer diseases, according to research team leaders Ricki J. Colman and Richard Weindruch. Their conclusion, as quoted in Nicolas Wade's July 2009 "New York Times" article, "Dieting Monkeys Offer Hope for Longer Life," is, "These data demonstrate that caloric restriction slows aging in a primate species." Colman and Weindruch say the data will likely translate to humans.
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