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Glycemic Index: Navigating the World of Sugars

Surges in blood sugar: more than just peaks and valleys!

In addition to understanding fibers and carbohydrates, it's worth exploring how your food choices affect your blood sugar levels. This knowledge comes in handy, whether you're diabetic, insulin-resistant, or simply want to avoid getting hungry shortly after a meal. Glycemic Index (GI) and Glycemic Load (GL) provide additional information in this regard.

Understanding macronutrients and using such terms have become part of everyday conversation. The topic may come up in places like the gym, hair salon, beauty parlor, or even during a friendly chat. "I won't eat any more carbs today to lose weight." "How many carbs are in this cake?" "I can't have watermelon because I'm insulin resistant. It's full of sugar!" "If I look at this pastry, my blood sugar skyrockets!" Sound familiar?

cubes of watermelon

Many things get mixed up during such discussions, and there are quite a few misconceptions. Moreover, as you already know, not all carbohydrates are the same, and sugar differs whether it's added or naturally part of the food. It's also crucial to consider the amount of fiber present. With an increasing number of people in our country dealing with diabetes and insulin resistance, it's essential to familiarize yourself with a concept that, without proper understanding, can easily lead carbohydrate counting astray. Shortly, you'll discover that, in addition to quantity and quality, questions like "what with what?" and "how?" matter.

No panic, no need for a dictionary!

This term brings you closer to understanding how various foods and meals affect your body, specifically your blood sugar levels. The goal isn't to memorize another definition but to grasp a few relationships. You don't need to learn numbers or tables; understanding the basics is sufficient. Afterward, it'll be much easier to navigate the store, market, or a restaurant. You'll better understand what to eat for prolonged satiety or quick energy for a workout or a sudden feeling of lightheadedness (hypoglycemia).

This concept is none other than the Glycemic Index, or GI

You've probably heard of it, but you might not be able to precisely define it. Let me help.

The Glycemic Index is a number indicating how the blood sugar-raising effect of a particular food compares to that of glucose. Glucose is taken as 100 in this case, and the GI of various foods is determined based on laboratory measurements, comparing their blood sugar effects to glucose.

We categorize them into three main groups:

  • High GI = 70-100 (e.g., potatoes, bananas, raisins, sugar)

  • Medium GI = 57-70 (e.g., durum pasta, oatmeal, oranges, grapes)

  • Low GI = 0-56 (e.g., apples, lentils, beans, tomatoes)

Checking the carbohydrate content of a product on the food label, a nutrient table, or a nutrition calculator app is not enough. It's crucial to consider the type of carbohydrates, the amount you're consuming, and even the preparation method, as well as what you're eating it with or drinking alongside it, all influence the glycemic index.

To better understand why mashed potatoes might have a higher glycemic index than oven-baked fries, you need to know what affects the GI!

low GI food next to a machine that checks blood sugar level

What Increases the Glycemic Index?
  • Grinding, extrusion (e.g. puffed rice compared to steamed rice)

  • Peeling (whole wheat flour compared to white flour)

  • Chopping, blending (fresh, raw fruit vs. a smoothie)

  • Cooking, pureeing (e.g. mashed potatoes, long-cooked oatmeal)

  • Overcooking rice or pasta until it becomes sticky (or examples like rice pudding and porridge)

  • Ripeness of fruit (visible and palpable in the case of bananas)

It's reasonable to ask: if the GI can be increased, can it be decreased too? Yes, that's exactly right. You can reduce the blood sugar-raising effect of a product or food (i.e., slow down the absorption of carbohydrates). This helps, for example, to stay satisfied longer, so you don't need to reach for a snack within 1-2 hours.

What Reduces the Glycemic Index?

  • Proteins (e.g. cottage cheese, lean meat with rice, pasta, or potatoes)

  • Fats (e.g. a piece of cheese with an apple, nuts in your cereal)

  • Fiber (e.g. vegetable side dish, pickles with pasta, choosing whole grain rice instead of polished rice, whole grain bread instead of white bread, opting for Brewer's Granola instead of instant oatmeal)

  • Cooking pasta “al dente”, not making it sticky, so it's "firm to the bite." The Italians know something, don't they?

  • Adding lemon or vinegar (as a salad dressing, in lemonades, or in pickles)

It's worth reading through these two lists several times and contemplating them. It will become clearer why, for example, for someone with diabetes or insulin resistance, it's not enough to just look at the grams of carbohydrates in the nutrient information. You shouldn't only consider an individual food item or raw material but also what you're eating it with. For example, nibbling on almonds, walnuts, or having a couple of bran cookies alongside a higher-sugar fruit makes a significant difference in preventing a sudden spike in your blood sugar levels. These small tricks also matter when planning your diet.

tészta főzés közben forrásban lébő vízben egy fazékban al dentére készítve

What Other Advantages Does Knowing the GI Have?

You might recognize GI from the past when the GI diet was popular, and many followed it for weight loss purposes. The idea behind it is that with a more stable blood sugar level—no significant spikes or crashes—by primarily consuming low or medium GI foods, it's easier to avoid overeating. There won't be sudden hunger, leading to uncontrolled snacking. So, overall, it is possible to lose weight with it, of course, along with regular physical activity.

Is There Anything Else?

We don't stop here because there's another number that might more accurately express how much of a particular food someone with diabetes and/or insulin resistance can eat. This is the Glycemic Load (GL). We use it less frequently in daily practice because it requires some calculation, which isn't necessarily practical during a busy weekday.

GL takes into account both the amount of food consumed and its carbohydrate content. The formula is: GL = (GI x carbohydrates per serving)/100.

The Glycemic Load value is also categorized into three groups:

  • High GL >20

  • Medium GL 11-19

  • Low GL 0-10

porridge toppings fruits, sauces, seeds, next to the bowl there is flower, blueberries and a purple scarf

For example, watermelon has a high GI (72), but its GL value is relatively low. A serving (120 grams) of watermelon contains 6 grams of carbohydrates, so the GL is calculated as follows: 72 × 6 /100 = 4.32. Accordingly, watermelon is considered to have a low GL value.

If you're diabetic, it's important not to eat a kilogram of watermelon at once, but it's not an entirely forbidden fruit. Try it with cheese or ham—it's not only an interesting flavor combination but can also mitigate the blood sugar-raising effect!

The above points are essential because, for example, if you're eating granola containing nuts, dried fruits, and olive oil, it affects your body differently than if you're having slow-cooked, almost mushy oatmeal. Their impact is different, but they have their roles and places in your diet. Moreover, you now know that you can "boost" oatmeal with seeds, nut butter, and fiber-rich fruits to reduce its glycemic index.

If you found this interesting, share the article with others!

In the next part, we'll delve into the date syrup, which - among many - sweetens Brewer's Granola as well.


Judit Schmidt dietitian, health educator, workplace well-being program manager. Engaged in prevention, education, and background work related to health, well-being, and nutrition. Provides assistance in conveying knowledge on nutrition, health, and well-being through article writing, blogging, editing, proofreading, and creating professional texts on these topics. Also conducts informative presentations for companies and schools. Her main focus is on disease prevention and creating a balanced and sustainable diet. Her motto: the sunny side of food. Dietitian Judit Schmidt presents her profession and works in a personal, occasionally humorous style on various social media platforms under the name Youteefool.


You can find Judit on her website:

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