What Exactly Is a High Glycemic Load?
To understand what is a high glycemic load number, it is essential to first know how it's calculated and what it represents. The concept of glycemic load (GL) was developed by Harvard researchers to provide a more complete picture of a food's effect on blood sugar than the glycemic index (GI) alone. While GI ranks carbohydrates based on how quickly they raise blood sugar, it does so for a standardized 50-gram portion of carbohydrate, which doesn't reflect real-life serving sizes. GL accounts for both the quality (GI) and the quantity of carbohydrates in a typical serving. A GL of 20 or higher is considered high, a moderate GL is 11–19, and a low GL is 10 or less.
How Glycemic Load is Calculated
Glycemic load is calculated using a simple formula: GL = (GI x grams of available carbohydrates) / 100. For example, a medium baked russet potato has a high GI of 111 and 30 grams of available carbs, resulting in a high GL of 33 ((111 x 30) / 100). In contrast, a cup of watermelon has a high GI of 76, but only 11 grams of available carbs, giving it a low GL of 8 ((76 x 11) / 100). This example perfectly illustrates why GL is a superior metric for gauging a food's actual impact on blood sugar.
The Health Implications of a High GL Diet
Consistently consuming a diet high in glycemic load can have significant health consequences. A high GL diet causes rapid spikes in blood glucose, which can lead to increased insulin demand and, over time, contribute to insulin resistance.
Health risks associated with a high GL diet include:
- Increased risk of type 2 diabetes: Numerous studies have linked high GL diets with a higher incidence of developing type 2 diabetes.
- Cardiovascular disease: Meta-analyses show that a high GL is associated with an increased risk of cardiovascular disease.
- Weight gain and obesity: Diets that cause significant blood sugar fluctuations can lead to increased hunger and cravings, making weight management more difficult.
- Fatigue: The rapid sugar crash that often follows a high GL meal can result in fatigue and decreased energy levels.
High GL vs. Low GL Foods: A Comparison
To highlight the difference, consider how different food choices can affect your body's glycemic response.
| Food Item | Typical Serving Size | Glycemic Index (GI) | Glycemic Load (GL) | Classification | Impact on Blood Sugar |
|---|---|---|---|---|---|
| Baked Russet Potato | 1 medium | 111 | 33 | High GL | Rapid and high rise |
| White Rice (boiled) | 1 cup | 66 | 35 | High GL | Rapid and high rise |
| Cornflakes | 1 cup | 79 | 20 | High GL | Rapid rise |
| Whole-grain Pumpernickel | 1 large slice | 46 | 5 | Low GL | Slow and gentle rise |
| Lentils (boiled) | 1 cup | 29 | 7 | Low GL | Slow and gentle rise |
| Apple (raw) | 1 medium | 39 | 6 | Low GL | Slow and gentle rise |
Strategies for Lowering Your Dietary Glycemic Load
Making dietary changes can significantly reduce your overall glycemic load and improve health outcomes. The focus should be on replacing high GL foods with lower GL alternatives and balancing meals with other nutrients.
- Choose less processed foods: Opt for whole grains, fruits, vegetables, and legumes in their natural state. For instance, swap out white bread for whole-grain options or eat whole fruit instead of juice.
- Combine carbs with protein and fat: Pairing carbohydrates with protein and healthy fats helps slow down digestion and minimize blood sugar spikes. A bowl of oatmeal (medium GI) becomes a lower GL meal when mixed with nuts or seeds and a splash of milk.
- Don't overcook starches: Cooking methods matter. Pasta cooked al dente (firm) has a lower GI and GL than overcooked, soft pasta. Similarly, consuming potatoes or rice after they've been cooked and cooled can lower their glycemic impact.
- Increase fiber intake: Foods high in fiber, especially soluble fiber, help slow down the absorption of carbohydrates. This is why legumes, vegetables, and whole grains are typically lower GL choices.
Conclusion
Understanding what is a high glycemic load number is a powerful tool for making informed food choices that support long-term health. A high GL value of 20 or more signifies a significant potential for blood sugar spikes, which are associated with increased risks of type 2 diabetes and cardiovascular disease. By focusing on incorporating more whole, unprocessed foods and pairing carbohydrates with protein and healthy fats, you can effectively manage your dietary GL. This shift in eating habits can lead to more stable blood sugar levels, improved energy, and a reduced risk of chronic illness.
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For further information and to check the GI and GL of many common foods, refer to the database from the University of Sydney: International Tables of Glycemic Index and Glycemic Load Values.
