What Is Glycemic Load (GL) and Why It Matters More Than GI?

18 Sep 2025 By Gregory W. Barsness, M.D.

What Is Glycemic Load (GL) and Why It Matters More Than GI?

Understanding how foods affect your blood sugar levels is crucial for maintaining overall health, especially for individuals managing diabetes or aiming for weight management. While the Glycemic Index (GI) has been a popular metric for years, the Glycemic Load (GL) provides a more complete and practical understanding of how different foods impact blood glucose. This article delves into what GL is, why it's more informative than GI, and how you can use it to make better dietary choices.

Quick Summary of Glycemic Load:

Glycemic Load (GL): A measure that combines both the quality (GI) and quantity of carbohydrates in a serving of food.
Why it Matters: GL gives a more realistic picture of a food's impact on blood sugar because it considers typical serving sizes.
Benefits: Helps in managing blood sugar levels, weight control, and overall dietary planning.

The Glycemic Index (GI): A Foundation, But Not the Full Picture

The Glycemic Index (GI) ranks carbohydrate-containing foods based on how quickly they cause a rise in blood glucose levels after consumption. The scale ranges from 0 to 100, with glucose assigned a value of 100 as the reference point. Foods are generally categorized as follows:

Low GI: 55 or less
Medium GI: 56 to 69
High GI: 70 or more

Foods with a high GI are rapidly digested and absorbed, resulting in a significant spike in blood sugar levels. Conversely, low-GI foods are digested more slowly, leading to a more gradual and manageable rise in blood glucose.

Limitations of the GI

While the GI is a useful tool, it has several limitations:

Doesn't Consider Serving Size: The GI only reflects the quality of carbohydrates but doesn't account for how much of the food is typically eaten.
Variability: The GI value of a food can vary due to factors like ripeness, cooking method, and processing.
Mixed Meals: GI values are typically measured for single foods consumed in isolation, which doesn't reflect real-life eating habits involving mixed meals.

For example, watermelon has a high GI of around 72. Based on this, one might assume it's not a good choice for blood sugar management. However, the amount of carbohydrate in a typical serving of watermelon is relatively low. This is where Glycemic Load comes in.

Glycemic Load (GL): The More Informative Metric

Glycemic Load (GL) addresses the key limitations of the GI by taking into account both the GI value and the serving size of a food. It provides a more accurate representation of how a typical serving of food will affect blood sugar levels. The Ultimate Glycemic Index Food List For Stable Blood Sugar

How GL is Calculated

The GL is calculated using the following formula:

GL = (GI x Grams of Carbohydrates per Serving) / 100

Interpreting GL Values

GL values are typically interpreted as follows:

Low GL: 10 or less
Medium GL: 11 to 19
High GL: 20 or more

Example: Watermelon Revisited

Let's revisit the example of watermelon. While it has a high GI of 72, a typical serving (about 1 cup) contains only about 11 grams of carbohydrates. Therefore, the GL of watermelon is:

GL = (72 x 11) / 100 = 7.92

This gives watermelon a low GL, indicating that a typical serving has a minimal impact on blood sugar levels, despite its high GI.

Table: Comparing GI and GL Values for Common Foods

| Food | Serving Size | GI | Carbohydrates (g) | GL | |-------------------|--------------|-----|--------------------|-------| | White Bread | 1 slice | 75 | 15 | 11.3 | | Brown Rice | 1 cup | 68 | 45 | 30.6 | | White Rice | 1 cup | 73 | 53 | 38.7 | | Potato (boiled) | 1 medium | 78 | 21 | 16.4 | | Sweet Potato | 1 medium | 63 | 20 | 12.6 | | Watermelon | 1 cup | 72 | 11 | 7.9 | | Apple | 1 medium | 38 | 21 | 8.0 | | Banana | 1 medium | 51 | 27 | 13.8 | | Carrots (raw) | 1 cup | 35 | 12 | 4.2 | | Chickpeas (canned)| 1 cup | 28 | 35 | 9.8 |

As the table shows, even though white rice has a similar GI to brown rice, the higher carb content gives it a substantially higher GL. This is why focusing on GL can give a more realistic picture of how the overall blood sugar will be impacted.

Why Glycemic Load Matters More Than Glycemic Index

Several reasons highlight why GL is a more practical and useful metric than GI:

Considers Portion Size: This is the most significant advantage. GL reflects real-world eating scenarios by factoring in how much of a food is typically consumed.
Better Blood Sugar Management: Using GL can help individuals make more informed choices about portion sizes and food combinations, leading to better blood sugar control.
More Realistic Dietary Planning: GL allows for a more flexible and balanced approach to meal planning, as it provides a clearer understanding of the overall glycemic impact of different foods.
Weight Management: By focusing on low to moderate GL foods, individuals can better manage their energy intake and maintain stable blood sugar levels, which can aid in weight management.
Applicable to Mixed Meals: While still best used as a guide, GL offers more insight when considering meals with multiple components, providing a cumulative assessment of glycemic impact.

Example: The Impact of Different Breakfast Choices

Imagine two breakfast options:

Option 1: A bowl of high-GI cereal (GI = 75) with 30 grams of carbohydrates. GL = (75 x 30) / 100 = 22.5 (High GL)
Option 2: A bowl of oatmeal (GI = 55) with 40 grams of carbohydrates. GL = (55 x 40) / 100 = 22 (Medium GL)

Even though the cereal has a higher GI, both options result in similar glycemic loads. This example illustrates how GL can help you compare different food choices more effectively, considering both the quality and quantity of carbohydrates.

Practical Applications of Glycemic Load

Here are some practical ways to incorporate GL into your dietary planning:

Choose Low-GL Foods as Staples: Prioritize foods with a low GL as the foundation of your meals. These include non-starchy vegetables, legumes, nuts, seeds, and whole grains like quinoa and barley.
Control Portion Sizes: Be mindful of portion sizes, especially for foods with a medium or high GL. Smaller portions will have a lower overall impact on blood sugar levels.
Combine Foods Wisely: Combine high-GL foods with foods that are high in fiber, protein, or healthy fats. These nutrients can slow down the absorption of glucose and reduce the glycemic impact of the meal. For example, pair a slice of bread with avocado or nut butter.
Read Food Labels: Pay attention to the carbohydrate content and serving size information on food labels. Use this information to calculate the GL of different foods.
Use GL Databases: Several online databases provide GL values for a wide range of foods. These databases can be a valuable resource for planning your meals.
Consult a Nutritionist: If you have specific dietary needs or health conditions, consult with a registered dietitian or nutritionist who can help you create a personalized meal plan based on GL principles.

Example: Meal Planning with GL in Mind

Consider creating a lunch that incorporates GL principles:

Main Dish: Grilled chicken salad with mixed greens, chickpeas, and a light vinaigrette dressing.
Estimated GL: Low to Medium (depending on the amount of chickpeas and dressing used)

This meal combines protein (chicken), fiber (greens and chickpeas), and low-GL carbohydrates, providing a balanced and sustained energy source without causing significant blood sugar spikes.

Considerations and Limitations of Glycemic Load

While GL offers significant advantages over GI, it is essential to be aware of its limitations: The Easiest Way To Read A Blood Sugar Test At Home

Variability: The GL values can vary based on the ripeness, processing, and cooking method of foods. Using GL databases as a general guide is more appropriate than as an absolute reference.
Individual Responses: Individual responses to different foods can vary due to factors like genetics, gut microbiome composition, and insulin sensitivity. It’s vital to monitor personal blood sugar responses to different foods to fine-tune your diet.
Nutrient Density: While managing blood sugar is important, focus on nutrient-dense foods to meet overall nutritional needs. Don't avoid healthy foods solely based on their GL values.
Complex Meals: Determining the exact GL of complex, mixed meals can be challenging. Focus on choosing predominantly low to medium GL ingredients and balancing macronutrients to mitigate the glycemic impact.

Recent Research Findings

A 2022 study published in the "American Journal of Clinical Nutrition" found that diets with a lower glycemic load were associated with improved glycemic control in individuals with type 2 diabetes. The study emphasized the importance of considering both the GI and carbohydrate content of foods for effective diabetes management.

Conclusion: Embracing Glycemic Load for Better Dietary Choices

The Glycemic Load (GL) provides a more comprehensive and practical understanding of how different foods affect blood sugar levels compared to the Glycemic Index (GI). By considering both the quality and quantity of carbohydrates in a serving, GL offers a more realistic assessment of a food's glycemic impact.

Incorporating GL principles into your dietary planning can help you make more informed choices, manage blood sugar levels, maintain a healthy weight, and optimize your overall health. While it is important to be aware of its limitations, using GL as a guide can empower you to create a more balanced and sustainable approach to eating. Remember, dietary advice should be tailored to your individual needs and health conditions. Consulting a healthcare professional or registered dietitian can provide personalized guidance on how to effectively use GL to optimize your health and well-being. What Are Normal Blood Sugar Levels Understanding Your A1C And Blood Sugar Chart