The glycemic index is a rating system that measures the effect individual, carbohydrate-containing foods have on blood sugar. Foods with a high glycemic index are digested quickly and raise blood sugar sharply. Those with a low glycemic index are not digested as quickly and have a less dramatic effect on blood sugar levels. A low-glycemic diet is a food plan based on carbohydrates with a low glycemic index value that might help some people maintain normal blood sugar levels.
Function
Only carbohydrates can raise blood sugar levels, so foods that are high in carbohydrates are a concern to anyone who has diabetes, pre-diabetes or other problems with blood sugar regulation. The glycemic index and glycemic load values were developed to distinguish between those carbohydrates that cause dangerous spikes in blood sugar and those that have only a mild effect. A low-glycemic diet featuring only foods that have a low glycemic index or glycemic load value helps stabilize or maintain normal blood sugar levels.
Effects
The glycemic index measures the change in blood glucose after a particular food is eaten. When a high glycemic food is eaten, blood sugar levels increase dramatically and this sends a message to the pancreas to produce enough insulin to remove all that sugar from the blood. The resulting high insulin level quickly reduces the amount of sugar in the blood, but this sharp reduction can have effects ranging from sudden hunger to hypoglycemia, or low blood sugar. A low glycemic diet limits this action and helps ensure a slower, sustained release of insulin and removal of sugar from the blood.
Foods
A low-glycemic diet includes many high-fiber foods such as bran cereals, vegetables, fruits and legumes, including dried beans and lentils. Foods from these groups have a glycemic index less than 55. It also includes non-carbohydrates such as meats and dairy products, which have no effect on blood sugar. Various forms of the same food, how that food is served and the types of foods it is served with will alter its actual effect on blood sugar. For instance, processing a low-glycemic food with other ingredients might raise the glycemic index of the final product. Eating a high-glycemic food on its own may cause a spike in blood sugar, while eating that same food as part of an otherwise low-glycemic meal might minimize its effect on blood sugar
Benefits
A low-glycemic diet can lower the risk of developing diabetes and heart disease, according to New York University's Langone Medical Center. Under a doctor's supervision, a low-glycemic diet may help reduce or eliminate symptoms in some children with seizure disorders.
Considerations
The glycemic index simply measures the effect of a type of food on blood sugar compared with other foods. To account for the amount of food eaten, scientists developed a glycemic load index using a formula based on the glycemic index and the number of grams of carbohydrate in a standard serving of food. According to Oregon State University's Linus Pauling Institute, glycemic load is a more dependable predictor of a food's effect on blood sugar.
References
- Harvard School of Public Health: Carbohydrates and the Glycemic Index
- New York University Langone Medical Center: Low Glycemic Index Treatment
- Massachusetts Institute of Technology: Glycemic Index
- Oregon State University/Linus Pauling Institute: Glycemic Index and Glycemic Load
- American Journal of Clinical Nutrition: International Table of Glycemic Index and Glycemic Load Values: 2002
