Glycemic Load vs Glycemic Index?

Glycemic index (GI) is a scaled measure from 1-100. The idea is to score the potential a food has to raise blood sugar. Food closer to 100 will effect blood sugar more than food closer to 0. A score under 55 is considered a low potential to raise blood sugar. All good information.

Here is the problem. Nutritious foods such as fruit, vegetables, and *whole grains can have a falsely elevated GI. Serving size and fiber are not considered in the calculation. GI is a based on consuming a serving that contains carbs equivalent to 50grams of sugar. That means mountains of fruit and vegetables. Who eats 1.5 pounds of carrots? 

And, like fruits and vegetables, the carbs in whole grains are wrapped in fiber and much slower to digest. The body has to work to extract the carbs so blood sugar is less effected.

Enter glycemic load (GL). GL is a measure of how blood sugar responds, but takes serving size and fiber into account. But don't be hasty to dismiss GI. While GL can be a more realistic measure, it relies on GI for its calculation.  

GL is calculated by multiplying the net carbs (carbs minus fiber) in a serving size by the GI, then dividing by 100. This comprehensive chart is from the Diabetes Journal.

If that seems complicated, make it easy. Eat fruit, vegetables, and whole grains for your carbs. 

A GL from 1-10 is considered to have little to no impact on blood sugar.

* Whole grains in this context are grains that have not been altered by processing. The difference between rolled oats and steel cut oats is a good example. 

While rolled oats are whole oats and have the same fiber as steel cut oats, they have been streamed, rolled, steamed again, and toasted. The processing makes rolled oats easier to digest, therefore they have a greater impact on blood sugar than steel cut oats.