The glycemic index changed how nutritionists view the health benefits of vegetables and other complex carbohydrates, according to "Carbohydrates and Health: Not that Simple.....of that Complex," a 2002 report by the Harvard Heart Letter. All vegetables were regarded as an ideal food for people who wanted to lose weight before 1981, but the glycemic index showed that some vegetables cause blood-sugar levels to spike rapidly. These spikes cause body fat, wrote the creator of the popular Atkins Diet.
History
Scientists have long known that blood-sugar spikes cause your body's pancreas to "churn out extra insulin," according to the "Carbohydrates and Health" report. High levels of insulin increase your risk of diabetes. Scientists thought that simple carbohydrates such as alcohol and sugar spurred much faster and higher blood-sugar spikes than complex carbohydrates such as beans, fruits, grains and vegetables. This premise was tested for the first time by University of Toronto researchers in 1981. "The results shattered long-held assumptions," according to the "Carbohydrates and Health" report.
Explanation
The measurement of how fast a food causes blood-sugar increases was labeled the glycemic index. All foods were compared to simple sugar, which was given a glycemic-index score of 100. Foods that cause blood sugar to increase twice as fast as simple sugar have a glycemic-index score of 200. Foods that cause blood sugar to increase half as fast have a score of 50. The University of Toronto researchers discovered that the starch in vegetables and other complex carbohydrates raises blood sugar very rapidly, "Dr. Atkins' New Diet Revolution" reported.
Statistics
Foods are high glycemic-index foods if their score is 70 or more and low glycemic-index foods if they score below 55, according to "Carbohydrates: Good Carbs Guide the Way," a Harvard School of Public Health report. Baked potatoes, sweet corn, carrots and green peas have scores of 85, 78, 71 and 68 respectively, but "The South Beach Diet" reports that many vegetables have a glycemic-index score below 20, including artichokes, asparagus, broccoli, Brussels sprouts, cabbage, cauliflower, celery, cucumbers, eggplant, green beans, lettuce, mushrooms, peppers, spinach, squash and zucchini.
Application
The high glycemic-index scores of starchy vegetables have changed many diets, because the Atkins Diet and South Beach Diet are based on the principle that high-carbohydrate, high glycemic-index foods cause body fat, while high-fat and high-protein foods don't cause fat because their glycemic-index scores are zero or close to zero. Starchy vegetables are banned during the first two weeks of the Atkins Diet and are discouraged by both diets. Low-fat diets like Ornish and Pritikin encourage all vegetables, but the glycemic index has affected vegetable consumption.
Significance
Eating vegetables with low glycemic-index scores can help you lose weight because high blood-sugar levels "have been linked with a variety of chronic diseases," according to Harvard's "Carbohydrates and Health" report. Lower blood-sugar levels can control or prevent type 2 diabetes, the report says. Vegetables with low glycemic-index scores also have a lot of fiber, which reduces blood-sugar spikes. High-fiber foods decrease your heart-disease risk because they reduce cholesterol, Atkins wrote.
References
- "Dr. Atkins' New Diet Revolution"; Dr. Robert Atkins; 2002
- "The South Beach Diet"; Dr. Arthur Agatston; 2003
- Harvard Heart Letter: Carbohydrates and Health: Not that Simple...or that Complex
- Harvard School of Public Health: Carbohydrates: Good Carbs Guide the Way
- "Dr. Dean Ornish's Program For Reversing Heart Disease"; Dr. Dean Ornish; 1996
- "The New Pritikin Program"; Robert Pritikin; 2007
