Glycemic Load

Glycemic Load (GL)

Carbohydrates with a low glycemic index (GI) and glycemic load (GL) result in a slower, more gradual rise in blood sugar, as illustrated in the figure above.

Foods with different GI and GL values influence blood sugar and insulin levels over time in this manner.

The glycemic index reflects how quickly a food raises blood sugar levels, while the glycemic load (GL) takes into account both the quality (GI) and the quantity of carbohydrates, thus providing a more complete picture of their impact.

Foods with a high GI (≥70) and high GL (≥20), shown by the red curve, cause a sudden spike in blood sugar levels, which peaks approximately 30 minutes after consumption.

This rapid increase triggers a significant insulin response, which then quickly lowers glucose levels, often below the baseline, potentially causing reactive hypoglycemia:

This blood sugar 'rollercoaster' is common with refined or processed carbohydrates that are absorbed quickly.

 

Foods with a medium GI (56–69) and medium GL (11–19), shown by the yellow curve (Figure 1), result in a more moderate rise in glucose and insulin levels, with a lower peak and a slower return to baseline.

This intermediate response is characteristic of foods with a balanced carbohydrate composition, which provide sustained glucose supply and avoid extreme fluctuations.

Foods with a low GI (≤55) and low GL (≤10), illustrated by the green curve (Figure 1), have only a minimal effect on blood sugar and insulin levels.

The gradual increase and sustained glucose availability are characteristic of high-fiber and complex carbohydrate foods, which help stabilize blood sugar and minimize excessive insulin release, supporting metabolic health.

 

However, GI and GL alone are not sufficient for nutritional decisions—a truly effective diet can only be developed by assessing composition, nutrient density, and individual response in a complex way.

This graph illustrates how foods with different glycemic index (GI) and glycemic load (GL) values affect blood sugar and insulin levels in the two hours following a meal.

 

The curves show the following

High glycemic index (Red curve)

• Values: GI ≥ 70, GL ≥ 20.
• Effect: Blood sugar levels rise suddenly and sharply, nearly reaching 2 g/L in just 30 minutes.
• Consequence: The body responds to this with a large release of insulin (up to 140 µU/mL).
• Afterward, blood sugar levels drop rapidly, often falling below fasting levels (reactive hypoglycemia), which can cause feelings of hunger.

 

Medium glycemic index (Yellow curve)

• Values: GI 56–69, GL 11–19.
• Effect: A more moderate rise, reaching the peak later, after about 1 hour.
• Consequence: The insulin response is also more moderate (about 75 µU/mL), and blood sugar levels return to normal more gradually.

 

Low glycemic index (Green curve)

• Values: GI ≤ 55, GL ≤ 10.
• Effect: Blood sugar levels rise slowly and only to a small extent.
• Consequence: This requires the least insulin (barely rising above the 10 µU/mL baseline) and ensures more stable energy levels in the long term.

 

In summary

Low-GI foods (green) help keep blood sugar levels stable, while high-GI foods (red) can cause a sudden "sugar shock" and subsequent feelings of fatigue.

 

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