Most of us would like to eat healthfully, and there’s no lack of advice on how to do so. You may have heard of the glycemic index, and you may have noticed “Low GI” labels on food packaging. The terms glycemic index and low or high GI get thrown around a lot, with or without a lot of understanding. And, like a lot of trendy diet terms, the hype often outstrips the truth.
But knowing what the glycemic index is, and how it pertains to your blood sugar goals, can be useful—especially as a person with diabetes. Being familiar with the glycemic index can help you make wise choices about your food as long as it’s treated as a helpful tool, not a miracle diet. Let’s go over how to use it to your advantage (without the hype):
1. What is it?
The glycemic index assigns a value to different foods based on that food’s affect on blood sugar. Foods are ranked on a scale from 0 to 100 in comparison to the effect of a standard amount of glucose. If a food causes a big rise in blood glucose, it’s categorized as a high GI food. Foods that have a high GI (like white bread) tend to break down quickly and cause a quick rise in blood sugar. Lower GI foods tend to break down more slowly and provide more sustained energy. Only foods with carbohydrates will have a GI rating.
2. People should use the glycemic index as a guide, not a rule book
The glycemic index is a useful tool for everyone, and people with diabetes can use it as a guide to help control their blood sugar. Someone experiencing low blood sugar can reach for a high GI food that will cause a quick uptick in blood sugar, and those looking for a steadier glucose release should look for lower GI foods.
The glycemic index is not a comprehensive guide for someone trying to better control blood sugar, but the American Diabetes Association thinks it may be helpful in “fine-tuning” the meals and snacks you choose for optimal glucose control.
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3. Multiple factors affect a food’s GI
It’s not just a food’s basic makeup that affect it’s rating on the GI scale, there are multiple GI-affecting factors to consider:
- Ripeness. Bananas that have been sitting on the counter and are starting to get brown are going to have a higher GI than greener bananas, and that will be true for all fruits and vegetables.
- Processing. If most of the work of breaking a food down has already been done, then the GI will be higher. Apple juice will have a higher GI than apple sauce, and white bread will have a higher GI than whole-grain bread. You get the picture.
- Cooking method. This one is related to processing. If you overcook pasta, for example, then it will have a higher GI than pasta that is cooked al dente. And if you bake or cook fruits or vegetables, they will have a higher GI than when they were raw (think raw carrots versus steamed).
- Fiber content. Generally, foods higher in fiber are lower on the GI scale as they have less of an effect on blood sugar.
4. It’s not the same for everyone
An article from Joslin Diabetes Center said, “Registered dietitians often encourage patients to determine their own individual glycemic index of foods based on how their blood glucose responds to the various meals and snacks they tend to eat.” As anyone with diabetes already knows, foods have different effects on different people. Always be suspicious of anything claiming to be the next great diet panacea—there is no one-size-fits-all eating plan.
5. The Scale
Here’s how the glycemic index scale works:
- Foods with a rating of 55 or lower are considered low GI foods
- Scores of 56 to 70 are considered medium GI foods
- 71 and above are high GI foods