Glycemic Load [Forum Archive]

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The Glycemic index is not practical because it ignores other health benefits a food may offer, it doesn't take into account the effect of eating a food as part of a meal that contains other components, like protein and fat, and most notably, it does not take serving size into account. For instance, carrots have a GI of 93 (high), but that number is based on eight or 10 fasting subjects who had to eat one and a half pounds of carrots, since it takes that much to total 50 grams of digestible carbohydrates (total carbohydrates minus fiber, in grams). A more practical way to use the information in the Glycemic Index is to convert it to Glycemic Load.

Glycemic Load (GL) takes a standard serving size into account, rather than just a fixed amount of carbohydrate. It is calculated by dividing the Glycemic index score discussed earlier by 100, and multiplying the result by the amount of available carbohydrate in a standard serving. Therefore, carrots' GL= 93/100 x four grams carbohydrate = four. A GL of 10 or less is low, 11-19 is moderate, and 20 or more is high. That's good news for watermelon, too, since it turns out that although the GI is high at 72, the GL for a four-ounce serving is four-very low. Watermelon offers fiber, vitamin C, and lycopene, which helps protect against prostate cancer.