Making Sense of Glycemic Impact
Caution: Consult your diabetes care team before starting a lower-carbohydrate meal plan. Diabetes medications such as insulin or oral drugs that stimulate insulin production (sulfonylureas or meglitinides) will need adjustment to prevent hypoglycemia (low blood glucose) when carbohydrate intake is decreased. In addition, meds might need to be decreased, and blood glucose levels need to be checked more often.
The Atkins Nutritional Approach is based on eating foods with the lowest glycemic impact. This can lead to improved blood glucose control, minimizing or eliminating the need for diabetes drugs for type 2s and possibly reducing the insulin dose for type 1s.
All carbohydrate foods raise blood sugar. The glycemic index (GI) represents how high and how fast this occurs with an individual food. Pure sugar, or glucose, raises blood sugar dramatically. So 50 grams of glucose (about 3 tablespoons), which has a designated value of 100, is the standard reference for the GI.
How Do You Ascertain the GI Ranking of a Food?
To ascertain the GI ranking of a food, healthy volunteers consume a measured portion of a carbohydrate food. Their blood glucose is monitored, and the effect is compared to that of sugar or white bread.
For example, a measured portion of potato raises blood glucose 85 percent as much as the standard does, so the potato’s GI ranking is 85.
Foods ranked from 0 to 55 on the glycemic index are considered to have a low GI. Those at 56 to 69 are considered to have a medium GI. Those at 70 and above have a high ranking.
The glycemic index is based on portions containing 50 grams of available carbohydrates. (Remember that the fiber in food is not digestible.) That may be a normal portion in the case of pasta; however, when it comes to high-fiber foods, it’s unrealistic.
For example, you have to eat six cups of carrots to consume 50 grams of carbohydrates. A normal portion of half a cup will actually provoke a much lower glycemic response.
The Glycemic Load
To be more precise, researchers developed the glycemic load (GL), a measure of the GI ranking multiplied by the number of grams of available carbohydrates per serving, which is then divided by 100. (The grams of available carbohydrate generally represent total carbs minus fiber.)
A GL of 10 or below is considered low; 11 to 19, medium; and 20 or more, high.
It is important to understand both the GI and the GL numbers, because research has shown that a high-glycemic diet is associated with higher blood glucose levels and an increased risk for heart disease.
The late Robert Atkins, MD, developed an easier-to-use tool that takes into account both the GI and GL, sorting foods into low, medium and high Atkins Glycemic Ranking (AGR). These three tiers make it easier to choose more healthful carbohydrate foods (See below). In general, low AGR foods contain the most fiber and can be eaten more frequently. Portion size and the number of grams of carbs must still be taken into consideration.
Not all low AGR foods are appropriate for the weight-loss phases of the Atkins diet. In addition, the amount of fat, protein and fiber in the meal can moderate the glycemic response of a single food.
A comprehensive list of foods and their AGRs can be found in “Atkins Diabetes Revolution” (William Morrow, 2004).
Food With a Low Atkins Glycemic Ranking
- Sunflower seeds
- Oatmeal (old fashioned)
- Wheat germ