The glycemic index forms the foundation for many popular weight-loss diets. These include a number of GI diets as well as South Beach, Glucose Revolution, the Insulin-Resistance Diet and Nutrisystem. The glycemic index replaces the simple/complex carbohydrate distinction with a more precise rating system, according to the American Journal of Clinical Nutrition. Using this updated classification system may help dieters better control both their appetites and their weight, according to the Linus Pauling Institute.
History
Researchers from the University of Toronto developed the glycemic index to help diabetics control their blood sugar levels. Nutritionists soon recognized the program's potential benefit as a weight loss tool for people struggling to stick to low-calorie diets.
Classification
The glycemic index rates foods according to how quickly they cause blood sugar to rise and then fall again. High GI foods result in an immediate and steep rise in blood sugar followed by a quick drop. Low GI foods cause a more gradual rise and fall that takes place over a longer period of time. A food with a glycemic index of 55 or lower is considered low glycemic. A rating above 70 is considered high. Foods with a high GI include white bread, white rice, pastries, candy, cookies, many crackers, potatoes and most root vegetables. Many books and online sources provide GI tables for quick reference.
Function
A high GI meal does not only cause your blood sugar to drop more quickly; it also causes it to dip further than it does after a low GI meal, according to the Linus Pauling Institute. This means you will be hungrier sooner -- and with a bigger appetite.
Effects
When a high-GI meal causes your blood sugar to drop significantly and quickly, you are left hungry again just a few hours after you eat. In contrast, a low-GI meal helps you to feel satisfied for a longer period of time. This may explain why low-glycemic diets result in significantly greater weight loss than high GI diets, according to the Linus Pauling Institute.
Contributing Factors
Factors that decrease the glycemic rating for a food include protein, fiber, fat and acid, according to the Harvard School for Public Health. Processing, refining and grinding increase the glycemic index.
Considerations
If you are using the glycemic index to lose weight, keep in mind that it is a tool to help you control your appetite and reduce calories. Making large meals out of low glycemic foods -- or adding high-fat or protein foods to a meal just to lower its glycemic index -- may introduce too many calories. To lose weight, you need to consume fewer calories than you burn.
Staples
Glycemic diets allow you to choose liberally from beans, vegetables, whole-wheat pasta, whole grains, nuts, lean protein and fresh fruit, according to the Harvard School for Public Health. Many diets use glycemic index research to promote low-carbohydrate, high-protein diets. However, the G.I. Handbook states the glycemic index is primarily intended help people choose -- not avoid -- much-needed, healthy carbohydrates.
References
- Linus Pauling Institute: Glycemic Index and Glycemic Load
- Harvard School for Public Health: Carbohydrates and the Glycemic Indez
- The G.I. Handbook: How the Glycemic Index Works; Barbara Rabage; 2005
