By Alina Sorvelyn

Updated on March 08, 2025

Glycemic Index vs. Glycemic Load – Why You Are Tracking Carbs All Wrong!

Glycemic Index (GI) and Glycemic Load (GL) measure the effect of how carbohydrates affect blood sugar in different ways.

Some carbohydrates cause a sharp spike, while others have a slower, steady impact.

Glycemic Index ranks how fast a food raises blood sugar. It compares foods to glucose, which has a GI of 100. A higher GI means a faster spike. But GI has a flaw. It ignores portion size. Watermelon has a high GI, but a typical serving has very little sugar.

Glycemic Load (GL) fixes this issue.

Glycemic Load calculates both the speed of digestion and the total carbohydrate content in a serving. It tells you how much you should eat.

It adjusts for serving size. It multiplies GI by the actual carbohydrate content per portion. This gives a more accurate picture of how food affects blood sugar. A food can have a high GI but a low GL if it has little digestible carbohydrate.

While both GI and GL measure carbohydrate impact, they differ in methodology, application, and practical dietary use.

For people managing diabetes, weight loss, or sugar cravings, this difference matters. A low-GI diet may not always prevent blood sugar spikes. A low-GL diet, however, accounts for both food type and portion size, making it more reliable for blood sugar control.

This article breaks down the key differences between GI and GL. You’ll see how each is calculated, how they impact health, and which one is more useful for your diet. By the end, you’ll know which number to trust when planning meals.

What Does GI and GL Measure?

Glycemic Index (GI)

Glycemic Index (GI) measures how fast carbohydrates raise blood sugar on a scale of 0 - 100. It measures the speed, not the total impact. High-GI foods digest fast and cause quick sugar spikes. Low-GI foods break down slowly, leading to a gradual rise.

GI is a relative scale. It compares foods against pure glucose, which has a GI of 100. A baked potato has a GI of around 85. That means it raises blood sugar almost as fast as glucose. An apple has a GI of 36. It releases sugar much slower.

Glycemic Index (GI) does not consider how much you eat. It only looks at 50 grams of carbs from a food. This creates misleading numbers. Watermelon has a high GI of 72, but a typical serving has very little sugar. Eating a normal slice won’t cause a huge spike.

Glycemic Load

Glycemic Load (GL) Measures the Total Blood Sugar Impact.

Glycemic Load (GL) tells you the real effect of food on blood sugar. It fixes the GI’s biggest flaw by adding portion size to the equation. GL uses this formula:

GL = (GI × Carbohydrate (g) per serving) ÷ 100

Glycemic Load makes a big difference. That same watermelon with a GI of 72 has a GL of only 4 per serving. That means it won’t spike blood sugar much. On the other hand, a bowl of white rice (GI 72) has a high GL of 32 because it has far more carbohydrates.

Glycemic Load gives practical information. It helps diabetics, keto dieters, and sugar-conscious eaters plan meals. Low-GL foods keep blood sugar steady. High-GL foods cause crashes and cravings.

GI is like measuring how fast a car is moving. GL is like measuring how far it travels. You need both to understand the full picture. Low-GI foods aren’t always low-GL. If you eat a huge portion, blood sugar still spikes. High-GI foods aren’t always high-GL either. If the portion is small, the impact stays low.

Why It Matters:

If you only look at GI, you might avoid healthy foods for no reason. If you only look at GL, you might underestimate blood sugar spikes from fast-digesting carbohydrates.

Now that we know what GI and GL measure, let’s see how they’re calculated. Understanding the math behind them explains why their numbers can be so different.

Calculation Difference: How GI and GL Are Derived

Glycemic Index (GI) and Glycemic Load (GL) have different calculation formulas that both measure how food affects blood sugar.

How Glycemic Index (GI) Is Calculated

GI ranks foods based on how fast they raise blood sugar. Researchers test this by feeding a person 50 grams of digestible carbohydrates from a specific food. Then, they track their blood sugar over two hours.

Next, they compare this response to pure glucose, which has a GI of 100. If a food raises blood sugar half as fast as glucose, its GI is 50. If it raises it just as fast, its GI is 100.

How Glycemic Load (GL) Is Calculated

GL goes one step further. It doesn’t just measure speed. It also considers how many carbs you actually eat.

The formula is simple:

GL = (GI × Carbohydrate (g) per serving) ÷ 100

For example, watermelon has a high GI of 72. But a typical serving only has 11 grams of carbohydrates. When you plug the numbers into the formula:

GL = (72 × 11) ÷ 100 = 7.9 (Low GL)

That means the actual blood sugar impact is low. This is why GI alone can be misleading. GL tells you the full picture.

Key Difference: Fixed vs. Flexible Measurement

Glycemic Index is fixed. It doesn’t change based on portion size.
Glycemic Load is flexible. It adjusts based on how much you eat.

Eating one spoonful of rice has the same GI as eating a whole bowl. But their GL is very different.

Why This Matters:

If you’re diabetic, on keto, or cutting sugar, knowing GI alone isn’t enough. GL helps you understand how much a food will really affect your blood sugar.

Bottom Line:

- GI tells you how fast a food spikes blood sugar.
GL tells you how much it actually impacts you.
Together, they help you make better food choices.

Next, let’s see how this plays out in real-life diets.

Dietary Implication: Choosing Foods Based on GI vs. GL

Glycemic Index (GI) ranks foods by how fast they raise blood sugar, but it ignores portion size, making it misleading; Glycemic Load (GL) adjusts for serving size, giving a more accurate picture of real blood sugar impact, which is crucial for diabetics, keto dieters, and those managing sugar intake.

GI Can Be Misleading Without Context.

The Glycemic Index only looks at how fast a food raises blood sugar, not how much of it people actually eat. Some healthy foods have a high GI but won’t cause major sugar spikes in real-life portions.

For example, if you avoid all high-GI foods, you might cut out healthy options unnecessarily.

GL Gives the Full Picture.

Glycemic Load corrects GI’s flaw by including serving size. It answers the real question: How much does this food actually affect blood sugar?

For example: A 158g bowl of white rice (GI 72, GL 32) has a greater impact than 1 cup of diced watermelon (158 g) (GI 72, GL 7.9).

Glycemic Load helps plan meals better. A food with a moderate GI but a high GL still causes a strong blood sugar spike.

Low-Carb Diets: Glycemic Load Matters More

Keto and low-carb dieters care about total carb intake. GL helps track that.

Example:

Carrots (GI 71, GL 6 per 100g) seem high-GI but don’t pack many carbs per serving.
Rice cakes (GI 82, GL 22 per 100g) are far worse for blood sugar.

Focusing only on GI leads to poor choices. GL is the better guide for keeping carbs low.

Diabetics Need Both Metrics

For diabetics, knowing both GI and GL helps balance sugar control and nutrition.

Low-GI, high-GL foods (whole wheat bread, GI 74, GL 18) can still cause spikes.
High-GI, low-GL foods (pumpkin, GI 75, GL 3) might be safe in moderation.

Using GI alone can cause mistakes. GL provides real-world accuracy.

If you're managing blood sugar, losing weight, or following keto, GI alone isn't enough. GL tells you how much a food truly impacts glucose levels. For real-life meal planning, GL wins.

Blood Sugar Impact: Short-Term vs. Long-Term Responses

Use GI to choose the right carbs. Use GL to control total sugar intake. Together, they create the best strategy for blood sugar balance. If you are diabetic, keto, or cutting sugar, GL is the better tool. It shows the real sugar impact of your meals.

GI can still help. It tells you which carbs digest slowly. But always check the GL to see how much sugar you’re actually eating.

Glycemic Index (GI) and Short-Term Blood Sugar Spikes.

High-GI foods like white bread, sugar, and cornflakes digest quickly. They send glucose into the bloodstream in a rush. This causes a sharp spike in blood sugar, followed by a crash.

For diabetics, these spikes are dangerous. They put stress on insulin production. Over time, repeated spikes can lead to insulin resistance, fatigue, and cravings. The body struggles to manage glucose. This can lead to unstable energy levels and hunger swings.

Low-GI foods, like lentils, nuts, and whole grains, digest more slowly. They release glucose at a steady pace, avoiding sharp highs and lows. This helps prevent sugar crashes and keeps energy stable.

Key takeaway: GI shows how quickly a food affects blood sugar, but it does not consider portion size.

Glycemic Load (GL) and Total Blood Sugar Impact

The Glycemic Load (GL) goes further. It calculates both the speed of digestion and the total carb content in a serving. This gives a clearer picture of a food’s real impact.

Take watermelon as an example. It has a high GI of 72. But a normal serving has very little carbohydrate.

Now, consider rice cakes. They also have a high GI, but they contain more carbs per serving. Their GL is much higher, meaning a greater sugar hit.

For diabetics and low-carb dieters, GL is a more useful measure. It helps balance blood sugar by factoring in how much you eat, not just how fast it digests.

Key takeaway: GL is a better tool for real-world meal planning because it includes portion size.

Why GL Matters More for Blood Sugar Control

Managing blood sugar isn’t just about avoiding spikes. It’s about controlling total glucose exposure over time.

High-GI diets can lead to chronic glucose swings. This triggers cravings, weight gain, and insulin resistance.
High-GL diets flood the body with too much sugar overall, even if the foods have a moderate GI.
Low-GL diets help maintain steady blood sugar. This supports fat loss, energy levels, and diabetes management.

Key takeaway: GL helps maintain long-term glucose stability. GI only tells part of the story.

Diabetes and Metabolic Health: Which One Matters More?

For diabetes and metabolic health, Glycemic Load is better than Glycemic Index because it accounts for both the speed and total amount of carbohydrates consumed, providing a more accurate measure of blood sugar impact in real-world portions.

Why GI Alone Falls Short?

Glycemic Index ranks food on a scale of 0 - 100. The higher the number, the faster the spike. White bread has a GI of 75. Brown rice has a GI of 50. That makes brown rice the better choice, right? Not always.

Glycemic Index ignores serving size. A small piece of white bread and a massive bowl of brown rice might have the same effect on blood sugar. That’s a problem. People eat food in portions, not in fixed 50-gram carb servings. This makes GI misleading when planning real meals.

Why GL Gives a More Accurate Picture

Glycemic Load considers both the speed and the amount of carbs in a normal serving.

Here’s how it works:

GL = (GI × Carbohydrate (g) per serving) ÷ 100

Let’s compare watermelon and white bread:

Watermelon (GI = 72, 6g carbs per serving)

GL = (72 × 6) / 100 = 4.3

White bread (GI = 75, 30g carbs per serving)

GL = (75 × 30 )/ 100 = 22.5

Watermelon has a high GI, but its GL is low because it has little sugar per serving. White bread, on the other hand, has both a high GI and a high GL. This means white bread will raise blood sugar much more than watermelon.

GI vs. GL for Diabetes Management

Diabetics need stable blood sugar. GI helps identify foods that cause fast spikes, but it’s not enough. GL is better because it shows total impact.

High GI, low GL foods (e.g., watermelon, carrots) are not dangerous
Low GI, high GL foods (e.g., large servings of pasta) can still spike blood sugar
A balanced diet uses both GI and GL together

Diabetes experts suggest using GL for daily planning and GI for food choices (Harvard Health, 2024). A diet full of low-GL foods helps keep blood sugar steady.

GL is More Useful for Long-Term Health

Diabetes increases the risk of heart disease, obesity, and metabolic syndrome. Controlling blood sugar long-term lowers these risks. Research shows that low-GL diets improve insulin sensitivity and reduce inflammation (American Diabetes Association, 2024).

Low-GI diets help but have limits.

A small bowl of low-GI oatmeal is good.

A giant bowl?

Not so much.

GL makes sure portions stay under control. That’s why it’s a better tool for real-world eating.

Next time you check a food’s GI, look at the GL too. It’s the real number that counts.

Weight Management: Low-GI vs. Low-GL Diets

Glycemic Load is better for weight management because it considers both the quality and quantity of carbs, giving a more accurate measure of their real impact on blood sugar and fat storage. Glycemic Index only measures how fast carbs raise blood sugar but ignores portion size, which can lead to overeating.

Losing weight is about controlling blood sugar and managing hunger. Both glycemic index (GI) and glycemic load (GL) play a role, but they work in different ways.

Low-GI Diet: Slower Digestion, Steady Energy

A low-GI diet focuses on eating foods that digest slowly. This helps prevent blood sugar spikes and crashes, which can cause hunger and cravings.

How it works: Foods with a low GI take longer to break down. This means blood sugar rises gradually instead of spiking.
Why it matters: When blood sugar stays stable, the body releases less insulin. High insulin levels trigger fat storage, so keeping insulin low can help with weight loss.
Limitations: GI only measures how fast carbs turn into sugar. It doesn’t consider portion size. Some high-GI foods, like watermelon, don’t have much impact because you eat them in small amounts.

Foods often recommended in a low-GI diet include:

Whole grains like oats and quinoa
Non-starchy vegetables
Beans and lentils
Nuts and seeds

Low-GL Diet: Controlling Portions, Reducing Sugar Impact

A low-GL diet takes things further. Instead of just looking at speed, it also considers the total amount of carbs in a meal. This gives a better picture of how food affects blood sugar.

How it works: The glycemic load formula factors in both GI and the number of carbs per serving. This helps measure the actual impact of food on blood sugar.
Why it matters: You can eat a high-GI food in small portions and still keep your blood sugar low. For example, a carrot has a GI of 71, but its GL is only 6 per serving—so it won’t spike your blood sugar.
More effective for weight loss: Low-GL diets focus on managing both carb quality and quantity. This makes them better for cutting sugar and losing fat.

Foods often recommended in a low-GL diet include:

Leafy greens (spinach, kale, lettuce)
Lean proteins (chicken, fish, tofu)
Healthy fats (avocados, olive oil)
Small portions of whole grains and fruit

A low-GI diet helps control hunger and energy. But a low-GL diet is better for real-world eating because it accounts for portion sizes.

If you follow only GI, you might still overeat carbs, thinking they are “safe.”
If you follow GL, you learn to balance portions, making weight loss easier.

For diabetics, keto dieters, and people struggling to quit sugar, a low-GL diet is the better choice. It helps control total carb intake without cutting out essential nutrients.

Focus on Low GL, Not Just Low GI

If you want to lose weight, control cravings, and avoid sugar spikes, focus on foods with a low Glycemic Load.

Practical Application: Dietary Plans Based on GI vs. GL

Use Glycemic Index to pick food that don't raise blood sugar too fast. Use Glycemic Load to track portion size and carbohydrates intake.

When to Use GI: Choosing the Right Carbs

GI helps pick carbs that don’t raise blood sugar too fast. Low-GI foods digest slowly, keeping energy steady. This is key for diabetics who need stable glucose levels. A low-GI diet also helps sugar cravings by avoiding sharp drops in blood sugar.

But GI has limits. It ignores portion size. Some high-GI foods, like watermelon (GI 72), seem bad. But a normal serving has little impact (GL 4). That’s where GL becomes useful.

When to Use GL: Controlling Sugar Load

GL matters when tracking actual carb intake. This is crucial for keto dieters and those lowering sugar. A small portion of high-GI food may not be harmful. A large portion of low-GI food can still spike glucose. GL shows the true effect.

For example, carrots have a GI of 71, making them seem like a problem. But a serving has only 6g of carbs, so GL is just 4. That’s low impact. On the other hand, a big bowl of brown rice (GI 50) adds up. If it has 50g of carbs, its GL is 25 - too high for someone managing sugar.

Is Glycemic Index or Glycemic Load Better for Meal Planning?

Neither is better alone. Both work together.

Use GI to pick quality carbs—slow digesting, steady energy.
Use GL to manage total sugar intake - keeping spikes low.

Diabetics should focus on low-GL meals. This avoids blood sugar highs and lows. Keto dieters should use GL to limit carbs, staying in ketosis. Sugar-free eaters should look at both GI and GL. They need carbs that don’t trigger cravings.

A diet based only on GI can mislead. A diet based only on GL can be too strict. The best plan combines both.

GI tells you how fast sugar hits. GL tells you how much sugar enters. If you manage blood sugar, GL matters more. If you choose healthier carbs, GI helps. Understanding both means smarter choices, better health, and easier sugar control.

Common Misconceptions: Myths That Blur the Differences

Many people mix up Glycemic Index (GI) and Glycemic Load (GL). This confusion leads to mistakes in food choices, meal planning, and blood sugar control. Let’s break down the biggest myths and set the facts straight.

Myth 1: High-GI Foods Are Always Bad

People assume that if a food has a high GI, it must be unhealthy. That’s not true.

Some high-GI foods, like carrots and potatoes, are packed with nutrients. Carrots have vitamins A and K. Potatoes provide fiber and potassium. These foods may raise blood sugar quickly, but that doesn’t mean they should be avoided.

What matters more is portion size. A small serving of a high-GI food has a lower glycemic load. That means it won’t spike blood sugar as much as a large serving. Instead of cutting out these foods, balance them with proteins, fats, and fiber to slow digestion.

Myth 2: Low-GI Foods Won’t Spike Blood Sugar

Low-GI foods digest slowly, but that doesn’t mean they can’t raise blood sugar. A massive bowl of brown rice or lentils still has a lot of carbs. Even though they have a lower GI, eating too much will still raise glucose levels.

GL matters here. If the total carbohydrate content is high, blood sugar will still climb. That’s why portion size and meal composition are more important than just looking at GI alone.

Myth 3: GI and GL Are the Same Thing

GI and GL measure different things. GI tells you how fast carbs turn into sugar. GL tells you how much sugar a full serving will produce in your body.

Take watermelon, for example. It has a high GI (72), meaning it digests quickly. But a typical serving has very few carbs, so its GL is low (4). This means eating a few slices won’t cause a big sugar spike.

On the flip side, a big bowl of brown rice has a low GI (50) but a high GL (23 per cup). That means it delivers a large sugar load over time. If you’re diabetic or on keto, this matters a lot. GL gives you the full picture.

Myth 4: Low-GI Means Low-Carb

Many people on keto think they can eat low-GI foods freely. That’s wrong. Some low-GI foods are high in carbohydrates. Chickpeas, sweet potatoes, and oats have a low GI but contain a lot of carbohydrates.

For keto dieters, total carbs matter more than GI. A food can have a slow impact on blood sugar but still push you out of ketosis if you eat too much. GI is helpful, but it’s not the main factor for a low-carb diet.

Myth 5: GI and GL Are Only for Diabetics

GI and GL are not just for people with diabetes. They help anyone who wants to control blood sugar, lose weight, or improve energy levels. Athletes use them to time carb intake. Keto dieters use them to balance carbohydrates limits. People quitting sugar use them to pick better alternatives.

Understanding GI and GL helps you make better food choices. It’s not just about avoiding sugar - it’s about managing carbohydrates the right way.

Don’t rely on GI alone. Don’t ignore GL. Use both together to keep blood sugar steady, control cravings, and stay healthy.

Glycemic Index vs. Glycemic Load – Which One Truly Matters?

GI helps pick better carbs. GL helps control total carb intake.

If you only use GI, you might eat too much of a "good" food. If you only use GL, you might miss the fact that some high-GI foods are still healthy.

The best approach is to use them together.

Choose foods with a low GI, but also watch how much you eat. That way, you keep blood sugar steady, control cravings, and stay on track with your health goals.