The glycemic index has changed how many nutritionists and doctors regard the nutritional value of carbohydrates, fats and proteins. Since the 1979 landmark U.S. Senate Select Committee on Nutrition report, governmental agencies and health-related organizations such as the American Heart Association have urged people to eat more carbohydrates and fewer fats and proteins. In recent years, though, the glycemic index's premise that carbohydrates are the primary cause of body fat has gained more credibility.
History
University of Toronto researchers led by David Jenkins devised the glycemic index in 1981. They were seeking to help diabetics by ascertaining which foods caused jumps in insulin. During their research, they concluded that foods that cause insulin increases also cause the sugar in your blood to rise; that excess blood sugar converts into body fat, reported the December 2002 issue of the "Harvard Heart Letter." The glycemic index's name comes from the fact that glycogen is a carbohydrate that is stored in your muscles and liver.
Explanation
The glycemic index measures how fast a food increases your blood sugar. Glucose, a simple sugar, was given a score of 100. Foods that increase your blood sugar half as fast as glucose have a glycemic index score of 50. Jenkins' team discovered that carbohydrates with low amounts of fiber increase blood sugar more than any other foods, while fats and proteins almost always have a negligible impact on blood sugar.
Significance
The glycemic index hasn't caused the U.S. Department of Agriculture (USDA) to change its recommendations on what to eat. It recommends that about 55 percent of your diet comes from carbohydrates, about 29 percent from fat and about 18 percent from protein. However, doctors Robert Atkins and Arthur Agatston feature the glycemic index in their 21st century diet books, and millions of people have used their diet plans, "Dr. Atkins' New Diet Revolution" and "The South Beach Diet" report. Both diets urge you to eat far more fats and protein and far fewer carbohydrates.
Health of Foods Redefined
The glycemic index changed the perception of many foods. The USDA's nutrition pyramid recommends that you eat more breads, cereals, pastas and rice than any other food. However, these foods are "high glycemic index foods" because their glycemic index score is higher than 70, reports the Harvard School of Public Health. Meats and cheeses have no score because only carbohydrates cause fat, Atkins reports.
Measuring Hunger
The glycemic index essentially measures which foods "satisfy your hunger longer and minimize your food cravings better," "The South Beach Diet" reports. According to Agatston, foods with low glycemic index scores change your body chemistry so you no longer crave fat-causing carbohydrates. That is why the Atkins and South Beach diets require you to eat only low-glycemic index foods for the first few weeks while banning most carbohydrates during this period. High-fiber foods are the only carbs the diets approve of because fiber "slows the entry of glucose into the bloodstream," Atkins reports. Most vegetables have glycemic index scores below 20.
References
- "The South Beach Diet"; Dr. Arthur Agatston; 2003
- "Dr. Atkins' New Diet Revolution"; Dr. Robert Atkins; 2002
- "Essentials for Health and Wellness"; Gordon Edlin, Eric Golanty, Kelli McCormack Brown; 2000
- Harvard Heart Letter: Carbohydrates and Health: Not That Simple...Or That Complex
- Harvard School of Public Health: Carbohydrates: Good Carbs Guide the Way
