Glycemic index and glycemic load are two terms that have come to light with the enormous popularity of low-carbohydrate diets. Although low-carb/no-carb diets are generally not recommended by most dietitians, research done on glycemic index and glycemic load of foods has taught us that choosing the right carbohydrates has a positive impact on our health.
Glycemic index ranks carbohydrates based on their glycemic response, or how quickly food is converted to blood glucose (blood sugar). Our bodies perform best when blood sugars are kept relatively constant. Eating large amounts of high glycemic index foods causes rapid rises and sharp falls in blood sugars, leading to fatigue, the feeling of hunger, and extra blood sugar being converted into stored fat. A glycemic index of 55 or below is considered low, and 70 and above is considered high.
Glycemic load refers to the quantity of food consumed, and is really the more important of the two. A glycemic load of 10 or below is considered low and 20 and above is considered high. To calculate the glycemic load of a particular food, multiply the glycemic index percent by the grams of carbohydrates per serving. For example, carrots have a high GI of 71. A standard serving size of carrots is ½ cup. There are 5 grams of carbohydrate in ½ cup of carrots, so the calculation would be .71 x 5 = 3.55, which is a low GL. Although carrots have a high GI, the GL is low due to the small serving size, and won’t cause sharp increases in blood sugar.
People with diabetes and insulin resistance can most benefit from choosing foods with a low glycemic load, since their ability to control and utilize blood sugars is compromised. Research has shown that a high glycemic load leads to low HDLs (the “good” cholesterol), increased triglycerides, increased C-reactive protein, and increased risk for diabetes and cardiovascular disease in people who have insulin resistance. In general, the benefits of consuming low GI and GL foods include lower post-prandial (post-meal) glucose levels; improved weight loss and insulin sensitivity; improved refueling of carbohydrate levels after exercise; increased satiety; and prolonged physical endurance.
For more information regarding glycemic index and glycemic load, and to find values of foods, log on to http://www.glycemicindex.com/
Sources:
“Glycemic Index, Glycemic Load, Satiety, and the Fullness Factor.” Retrieved February 7, 2005 from nutritiondata.com
Bell, SJ, Sears B. “Low Glycemic Load Diets: Impact on Obesity and Chronic Diseases.” Critical Reviews in Food Science and Nutrition. 43(4):357-377, 2003.
Article by Allison McCall Francis, RD, LD, CNSD
