Carbohydrates and Glycemic Load

You probably know that un-processed, no-sugar-added foods are healthiest. But why should you choose, say, whole wheat bread over white bread or fresh fruit over fruit juice? It all boils down to the way that certain foods affect your blood sugar levels, or the food’s glycemic index. Here, we’ve outlined the science behind the glycemic index and glycemic load, and conclude with recommendations for your diet.

Energy from food is circulated in the bloodstream as glucose (blood sugar) and stored as fat throughout the body as well as small amounts of glycogen in muscles. The brain relies on glucose for fuel, but too much glucose in the blood can be harmful. Therefore, it is very important that blood glucose levels stay at a steady level. Insulin is the hormone in charge of maintaining blood glucose levels at a steady level. After we eat, insulin levels increase, prompting our cells to absorb excess glucose available from the foods we just consumed and store it for later use. The type of foods we eat, and their combination in meals, has a large impact on our blood sugar levels after meals and can either help this system work well by not challenging our bodies with large doses of glucose at one time or stress it by putting a lot of glucose into the blood stream quickly. The glycemic load takes into account the glycemic index of a food and provides a measure of the relative glycemic impact of a “typical” serving of that food or meal and can be more helpful to use when making food choices.  A food’s glycemic load is a measure of that food’s impact on your blood sugar and insulin levels. A lower glycemic load translates to a smaller effect on blood sugar and insulin levels. Many factors contribute to a food’s glycemic load, including level of processing (more processing=higher glycemic load); fiber content (higher fiber=lower glycemic load); fat, protein, and acid content (higher fat, protein, or acid = lower glycemic load); and total grams of carbohydrate per serving (higher carbohydrate = higher glycemic load). Examples of foods with low, medium, and high glycemic load are below. We recommend choosing more foods with a low glycemic load and fewer foods with a high glycemic load.

Low glycemic load

·       High-fiber fruits and vegetables (½ cup broccoli, Brussels sprouts, raspberries, 1 cup strawberries, 1 medium pear, apple, 1 large orange, ½ an avocado)

·       Bran cereal (1 oz)

·       Beans and legumes, such as chick peas, kidney beans, black beans, lentils, and pinto beans (5 oz cooked, approximately ¾ cup)

·       Nuts (1-2 oz)

Medium glycemic load

·       Pearled barley (1 cup cooked)

·       Brown rice (¾ cup cooked)

·       Oatmeal (1 cup cooked)

·       Whole grain breads (1 slice)

·       Whole grain pasta (1 ¼ cup cooked)

High glycemic load

·       Baked or boiled large potato (10 oz)

·       French fries (medium serving at McDonald’s, 5 oz)

·       Refined breakfast cereal (1 oz)

·       Sugar-sweetened beverages (12 oz)

·       Candy bars (1 2-oz bar or 3 mini bars)

·       Fruit juice (8 oz) (note, this includes fruit juice with no added sugar)

·       White rice (1 cup cooked)

·       White pasta (1 ¼ cup cooked)

If you currently eat the foods below in the left column, try to replace them with the suggested substitutions in the right column:

 

See a list of the glycemic index and glycemic load for the most common foods at http://www.health.harvard.edu/newsweek/Glycemic_index_and_glycemic_load_for_100_foods.htm

Source: The Harvard School of Public Health Nutrition Source