Glycemic index (GI) and glycemic load (GL) for glucose health

Dec. 17, 2024 • 4 min read

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The content in this article should not be taken as medical advice. Please consult with your healthcare provider regarding your individual health needs.

When it comes to healthy eating and glucose management, carbs often take center stage in discussion. But not all carbs are created equal. Luckily, we’ve got the glycemic index (GI) and glycemic load (GL) to help us sort it out.

Both are useful tools, though most people aren’t quite sure how they work or why they matter. But here’s the thing: it’s all a lot simpler than it sounds.

What’s the glycemic index?

The glycemic index (GI) measures how quickly a carb-containing food raises your blood sugar levels after eating. Foods are scored on a scale of 0 to 100, with pure glucose (sugar) at the top of the scale. The idea is simple: foods that break down quickly in the digestive system release glucose faster into your bloodstream, spiking your blood sugar.

Low GI foods (55 or less) break down slowly, leading to a more gradual increase in blood sugar. Examples include most fruits, non-starchy vegetables, legumes, and whole grains like barley or oats.
Medium GI foods (56-69) have a moderate effect on blood sugar. This might include foods like whole wheat bread or brown rice.
High GI foods (70 and above) are fast-digesting and quickly elevate your blood sugar. Think of foods like white bread, cereals, and sugary snacks.

What’s glycemic load?

Glycemic load (GL) takes the glycemic index a step further. While the GI gives you a sense of how fast a carbohydrate is digested, it doesn’t tell you how much carbohydrate is in a typical serving size. This is where glycemic load comes in—it factors in both the quality (GI) and the quantity (amount of carbs) of the food. In short, GL is a more practical tool for understanding the overall blood sugar impact of a food, given that portion size matters in real life.

Here’s how foods are categorized by glycemic load:

Low GL (10 or less): Minimal impact on blood sugar.
Medium GL (11-19): Moderate impact on blood sugar.
High GL (20 or more): Significant impact on blood sugar.

For example, watermelon has a high GI because it raises blood sugar quickly, but it’s mostly water and low in carbohydrates. Its glycemic load is actually quite low. This means that even though it might be digested quickly, it doesn’t pack enough carbs to have a significant long-term impact.

Why do GI and GL matter for your health?

Understanding GI and GL can be a game-changer when it comes to managing your diet, especially for people focusing on their glucose levels. Here are a few key benefits:

Glucose health: Low-GI and low-GL foods result in steadier blood sugar levels, which is crucial for managing diabetes or prediabetes. This can also reduce the risk of insulin spikes that lead to energy crashes and cravings.
Sustained energy: Since low-GI foods break down more slowly, they provide a steadier stream of energy. This is helpful if you want to avoid feeling sluggish between meals.
Weight management: Because low-GI foods help maintain blood sugar balance, they may help curb cravings and reduce overeating. They also tend to be higher in fiber, which promotes a feeling of fullness.

Putting it all into practice

So, how can you use glycemic index and glycemic load to improve your diet?

Opt for low-GI and low-GL foods

Whenever possible, choose foods that are low on both scales. This means plenty of non-starchy vegetables, fruits like apples and berries, legumes, and whole grains like quinoa and oats.

Don’t shun all high-GI foods

Some high-GI foods, like potatoes or rice, have valuable nutrients. The trick is to pair them with other low-GI foods (like vegetables or protein) to balance out the blood sugar response. For instance, adding chicken to a baked potato can lower its overall glycemic impact.

Portion control matters

Even foods with a low glycemic index can cause blood sugar spikes if eaten in large quantities. Glycemic load is your friend here, reminding you that the amount you eat is just as important as the type of carb you choose.

Read between the lines

GI and GL are helpful, but they aren’t the full picture. For example, some processed foods might technically have a lower GI than you'd expect because they contain fat, but that doesn’t make them a healthy choice. It’s always important to consider overall nutrition.

The bottom line

The glycemic index and glycemic load are valuable tools to help you understand how different carbs affect your blood sugar. By focusing on low-GI and low-GL foods, you can maintain steadier energy, support healthy weight management, and help regulate blood sugar. But remember, it’s all about balance. No single food will make or break your diet. Instead, consider GI and GL as part of a broader, nutrient-rich eating plan tailored to your unique needs.