Carbohydrates are often divided into two categories -- simple and complex. Simple carbohydrates include mono- and disaccharides (i.e. fruit sugars and table sugars) and tend to be absorbed faster than complex carbohydrates or polysaccharides (i.e. breads, pasta, grains). However, due to the varying rates of digestion and absorption between different carbohydrates, such simple classifications may not always be the most useful.
What is the glycemic index?
Foods are assigned glycemic index numbers based on the comparative increases in blood glucose (sugar) levels they produce when eaten.
A low- to moderate-glycemic food causes a slow, gradual rise in blood sugar, and maintains the increased energy level for a longer duration.
A high-glycemic food increases the blood sugar concentrations quickly, thus providing energy to the body in a short period of time. However, insulin is released in response to this rise in blood sugar, which, in turn, brings the blood sugar down fairly rapidly. This rapid decrease reduces the energy supply and may trigger hunger.
How is the glycemic index
By comparing the area under the graphed line with that obtained from consuming 50 grams of pure glucose, a percentage is determined. For example, a glycemic index of 60 indicates that consuming 50 grams of that food causes an increase in blood glucose 60 percent as great as that produced by eating 50 grams of pure glucose.
Many factors can influence the glycemic index. Often foods with different glycemic indexes are consumed simultaneously, which affects the glycemic index of the individual foods. In addition, other factors that can influence the glycemic index include:
Why is the glycemic index
Due to the importance of balancing blood glucose levels in diabetics, low to moderate glycemic foods are recommended to moderate blood glucose in these individuals.
Athletes often choose foods that optimize their glycogen stores. Most athletes benefit the most from eating foods having a low to moderate glycemic index in their pre-game meal, and then eating high-glycemic foods immediately after exercise.
However, the post-activity meal also should contain low to moderate glycemic foods for optimal glycogen storage.
Proponents and critics debate both the merits of the glycemic index and how it is calculated.
Clinical trials researching meals with different glycemic indexes confirm that eating low-glycemic foods helps blood glucose levels stay more level and thus reduces the amount of insulin released after a meal.
When blood glucose levels are fairly even between meals, fat is also metabolized at a healthier rate so blood lipid levels remain comparatively even.
Monitoring the glycemic index for various foods is one way diabetics can try to control their blood glucose levels. Studies where dietary habits have been examined indicate that foods with higher-glycemic indexes are a risk factor for diabetes, obesity, and cardiovascular disease.
Groups consuming high-glycemic foods were at greater risk of developing chronic disease than did the groups consuming foods with lower glycemic indexes. Critics have raised several concerns regarding how the glycemic index is calculated.
The glycemic index can vary with varieties within a food group, method of preparation, growing conditions, geographic locations, genetic strain, ripeness, acidity, fiber, protein, and fat content of foods.
Current research is investigating whether rapid fluctuations in blood glucose levels increase the risk of fat gain and type 2 diabetes.
For additional glycemic indexes visit these Web sites:
Breads & Grains
Glycemic Indexes of Common Foods Foods are listed from highest to lowest glycemic index within the category. Glycemic index was calculated using glucose as the reference with glycemic index of 100. (The University of Sidney, www.glycemicindex.com). No endorsement of companies or their products is intended nor is criticism implied of similar companies or their products that are not included.