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Glycemic Load

General

Glycemic Load (GL)

Glycemic index adjusted for actual portion size, giving a more practical estimate of how a real serving of food affects blood sugar.

Definition

Glycemic Load (GL) estimates a food's real-world blood sugar impact by combining its glycemic index with the actual amount of carbohydrate in a typical serving, rather than a standardised 50g reference portion. This makes GL a more practical number for meal planning, since it reflects how much of the food you're actually eating.

The Glycemic Load Calculator performs this calculation from a food's GI value and its carbohydrate content per serving.

Formula

Glycemic Load = (GI × Carbohydrate grams per serving) ÷ 100

Worked Example

Watermelon has a GI of about 76 (high) but only about 8g of carbohydrate in a typical 120g serving:

GL = (76 × 8) ÷ 100 = 6.1 (low glycemic load)

Compare this to white rice, with a GI of about 73 and roughly 45g of carbohydrate in a typical serving:

GL = (73 × 45) ÷ 100 = 32.9 (high glycemic load)

Key Things to Know

  • GL is more actionable than GI alone: it reflects your actual portion, not a standardised reference amount.
  • A high-GI food isn't automatically a high-GL food: portion size and carb density both matter, as the watermelon example shows.
  • Pairing foods changes the real-world effect: protein, fat, and fiber slow digestion and blunt blood sugar response even though they don't change the calculated GL.
  • Useful for both diabetes management and general nutrition: GL matters for blood sugar control, energy stability, and athletic performance planning alike.

Related Calculators

Glycemic Load Calculator →Calculate glycemic load from a food's glycemic index and carbohydrate content per serving, and see whether it falls in the low, medium, or high GL range.
Glycemic Index Calculator →Look up the glycemic index of common foods and see whether it falls in the low, medium, or high GI category, plus an estimated glycemic load per serving.
Carb Calculator →Calculate your ideal daily carbohydrate intake in grams based on your TDEE and macro split goal, from low-carb to high-carb endurance diets.

Related Terms

Glycemic IndexGlycemic Index (GI)

Frequently Asked Questions

A glycemic load under 10 is generally considered low, 10–19 medium, and 20 or above high. These ranges are guidelines rather than strict clinical cutoffs.
Yes — watermelon is a classic example, with a high glycemic index but a low glycemic load in a typical serving because it contains relatively little carbohydrate per portion despite that carbohydrate being quickly absorbed.
GL reflects your actual serving size, while GI alone can be misleading if you don't also account for how much of the food you're eating — a large portion of a moderate-GI food can have a bigger blood sugar impact than a small portion of a high-GI food.
Calculate the GL of each individual food component in the portion you're eating, then add them together for the meal's total glycemic load.
The calculated GL of an individual food doesn't change, but eating it alongside protein, fat, or fiber slows overall digestion and tends to blunt the actual blood sugar spike compared to eating that food alone.