The glycemic index (GI), a system that ranks foods on a scale of 1 to 100 by how quickly they convert to glucose and raise blood sugar levels, has been replaced by the GL – the glycemic load. The GL compares a food’s GI score with the amount of calories and carbs in the food. The GL is the most practical way to use the GI for helping a client lose weight. It is easily calculated by multiplying a food’s GI (as a percentage) by the number of net carbohydrates* in a serving. That number, or the GL, provides a ballpark indicator of how much that serving of food will increase a client’s blood-sugar level.
GL = GI/100 x Net Carbs*
*Net Carbs are equal to the Total Carbohydrates minus Dietary Fiber
In general, a GL below 10 is considered “low,” while a GL above 20 is “high.” The glycemic load is a much better indicator of a food’s ability to prevent or contribute to disease, since a food that has a large amount of carbs AND dramatically raises blood sugar levels increases the chances of weight gain more than a food that might temporarily raise blood sugar levels, but has few calories. For example, a potato has a high glycemic score and it packs a bunch of carbs, so it’s GL is very high – 26. In contrast, watermelon has a high GI score, but few calories or carbs, which explains why its GL is only 4. The former will increase the chances of those extra calories being funneled into fat cells, but watermelon just fills you up, without filling you out.