What is the Glycemic Index?

age-related macular degeneration animal protein anxiety blood glucose cancer carbohydrates cardiovascular health chronic inflammation cytokines depression diabetes elimination diet fats fiber fruits glucose glycemic index grains heart disease mental health obesity oils pasta pro-inflammatory diet vegetables weight loss Nov 04, 2023

Foods with low glycemic index vs foods with high glycemic index

Have you ever tried to shed pounds or be healthier by skipping carbohydrates? If you have, you’re not alone. After all, popular diets have long tied carb intake to weight gain and other health issues.¹

In fact, not all carbs are created equal. Some of them make your blood sugar levels rise quickly. Frequent spikes in blood sugar can cause insulin resistance and inflammation. These conditions are linked to chronic problems like obesity, type-2 diabetes, and heart disease.^2,3,4

That’s why it’s important to choose the right types of carbs to eat. The glycemic index can help you make healthy carb choices.²

In this article, we’ll talk about:

How’s the glycemic index measured?
What factors affect the glycemic index?
What are the glycemic index values for some common foods?
How can a diet with a low glycemic index benefit your health?

Let’s start by defining “glycemic index.”

How’s the glycemic index measured?

The glycemic index is a ranking system for carbohydrates. It shows how quickly a carb-containing food gets converted into glucose, and thus how fast your blood sugar level will rise after eating it.^5,6

Usually, glycemic index values are calculated by measuring blood sugar levels in non-diabetics. First, blood sugar levels are measured over a two-hour period after eating a test food containing 50 grams of carbs. This value is then compared to blood sugar levels after eating 50 grams of pure glucose.^5,7

What factors affect the glycemic index?

The glycemic index of a food depends on its processing and form. The food’s fiber and acid content also play a role. Other factors include ripeness, cooking time, and combinations with other foods.^5,8

The more processed a food, the faster you digest it. In other words, processing tends to increase a food’s glycemic index. For instance, instant oatmeal has a higher glycemic index than steel-cut rolled oats^5,8

Fiber is a complex carbohydrate that your body can’t digest. So, fiber-rich foods tend to have a low glycemic index.^8,9

Acidic foods have a low glycemic index because it takes time to break them down into sugar. This explains why sourdough bread, which is made with lactic acid, has a lower glycemic index than white bread.^5,8

Most fruits contain starch. This complex carbohydrate gets broken down into sugars during the ripening process. Thus, ripe fruits tend to have a higher glycemic index than unripe ones.^8,10

Likewise, cooking breaks down starches. The longer you cook foods like pasta, the easier they are to digest. This means that a food’s glycemic index increases with cooking time.⁵

Finally, you can combine high-glycemic foods with low-glycemic ones to manage your blood sugar better. That’s because a meal’s glycemic index is based on the average of the glycemic index values of all the meal’s components. Following this rule, you can choose to pair rice with meat and leafy vegetables. Or you could add cheese to a slice of bread for a lower overall glycemic index.⁵

What are the glycemic index values for some common foods?

High-glycemic foods have a GI of 70 to 100. In this group are potatoes, cornflakes, instant oatmeal, and white bread. The highest value of 100 goes to pure glucose.²

Foods with glycemic index values from 56 to 69 are considered medium-glycemic. Examples are pineapple, pumpkin, popcorn, and brown rice.^2,7

Dairy products, including whole milk, skim milk, and yogurt, have a low glycemic index between 21 and 55. Fruits and vegetables like bananas, carrots, mangoes, oranges, and taro are low-glycemic as well. Some grains and noodles — for instance, rolled oats, rice noodles, and spaghetti — also fall into this category.^2,7

Several vegetables have a glycemic index of 20 or less. Among these ultra-low-glycemic veggies are asparagus, broccoli, cauliflower, cabbage, celery, and cucumber. Also on the list are eggplant, radish, spinach, and zucchini.¹¹

Other foods with an ultra-low glycemic index are olives, avocado, bran (wheat or oat), and vinegar.¹¹

Lastly, non-carbs have a glycemic index of 0. They include animal proteins such as eggs, chicken, pork, beef, lamb, veal, and fish. The glycemic index of fats and oils is 0 too. Some of these food items are butter, margarine, olive oil, canola oil, and safflower oil.^2,11

How can a diet with a low glycemic index benefit your health?

Eating low-glycemic foods may help you lose weight. Plus, it can aid you in managing or preventing several chronic diseases.¹²

Low-glycemic foods tend to be rich in protein or fiber. So, eating them can make you feel full longer compared to high-glycemic foods. That feeling of fullness can reduce your food intake, promoting weight loss.¹²

And of course, a low-glycemic diet stabilizes your blood sugar levels after meals. When your blood sugar levels are stable, your body doesn’t have to release a lot of insulin. Low insulin levels mean less fat storage. This effect, along with reduced hunger, explains why a low-glycemic diet can help treat obesity.^12,13

Also, studies show that low-glycemic diets can decrease hemoglobin A1C (a marker of average blood sugar level over three months). They reduce levels of fasting blood sugar too. For these reasons, eating low-glycemic foods is a good way to control your blood sugar if you’re diabetic. And even if you’re not, it’s still a good idea to include them in your diet to help prevent diabetes.^14,15

Other studies suggest that a low-glycemic diet can prevent heart and blood vessel disease. It can also lower your risk of certain cancers, including breast and colorectal cancer.^16,17,18,19

Low-glycemic foods may protect against age-related macular degeneration (AMD) as well. AMD happens when a part of your retina becomes damaged, and it tends to get worse over time. It’s the main cause of vision loss for people aged 50 and above.^20,21

Foods with a low glycemic index can enhance your mental health too. In particular, they can reduce your risk of depression and anxiety.^22,23

Chronic inflammation is a major contributor to the physical and mental conditions above. Blood sugar spikes due to high-glycemic foods cause stressful conditions for your cells. The stress, in turn, increases cytokines like interleukin-6 (IL-6) and tumor necrosis factor-ɑ (TNF-ɑ). These signaling proteins promote inflammation.^24,25

To sum it up, low-glycemic diets fight chronic inflammation and disease through their stabilizing effect on blood sugar levels.

Conclusion

The glycemic index is a handy tool for choosing high-quality carbs for your diet. Opt for low-glycemic foods to improve your blood sugar control and enjoy various health benefits.

There’s so much more to health than a low glycemic index though. You have a unique body with unique needs and pain points. You’ll need to consider these factors to identify the foods that bring out your best (and worst). Interested in personalizing your diet for maximum health and performance? Click here to learn more.

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