Understanding the Glycemic Index

The glycemic index is a powerful but often misunderstood tool. It's not enough to classify foods as "good GI" and "bad GI": glycemic load, food combinations, and the context of the meal play an equally important role. This guide gives you the keys to using these concepts in a practical and realistic way.

Steps

1

Understand the GI scale

The glycemic index ranks foods from 0 to 100 based on how quickly they raise blood sugar compared to pure glucose (GI = 100). There are three categories: low GI (below 55), moderate GI (56 to 69), and high GI (70 and above). This classification guides your daily choices.

2

Identify high and low GI foods

High-GI foods: white bread (75), white rice (73), baked potatoes (78), cornflakes (81). Low-GI foods: lentils (32), chickpeas (28), sweet potato (63), apple (36). Familiarize yourself with the GIs of foods you eat regularly.

3

Distinguish GI and glycemic load

GI doesn't account for the amount consumed. Glycemic load (GL) corrects this by multiplying the GI by the amount of carbs in a real portion. Watermelon has a high GI (76) but a low GL (4) because it contains few carbs per serving. GL is what counts in practice.

4

Combine foods strategically

Adding protein, fats, or fiber to a high-GI food lowers the overall glycemic response of the meal. White bread alone has a GI of 75, but a sandwich with chicken, avocado, and salad has a much more moderate glycemic response. The complete meal is more important than the isolated food.

5

Apply to your meal planning

For your daily meals, choose a low or moderate GI base (whole grains, legumes), add protein and healthy fats, and complete with vegetables. Save high-GI foods for during or after physical exercise, when the body uses them efficiently.

GI vs Glycemic Load: the true measure

The glycemic index is measured in a lab on 50 g of available carbs from a given food, but no one eats 50 g of carbs from watermelon at once (you'd need to eat 700 g). Glycemic load solves this by considering the actual portion.

Formula: GL = (GI x grams of carbs per portion) / 100. A GL below 10 is low, between 11 and 19 is moderate, and 20 or above is high. This measurement is much more useful daily than GI alone.

Concrete example: cooked carrots have a GI of 47, and an 80 g portion contains 4 g of carbs, making a GL of 2. No need to avoid them despite popular fears. Conversely, a bowl of white rice (150 g cooked, GI 73, 40 g carbs) has a GL of 29, which is high.

Impact on energy and hunger

When you eat a high-GI food on an empty stomach, your blood sugar rises quickly, triggering a strong insulin secretion. Insulin causes blood sugar to drop, sometimes below the initial level, causing fatigue, loss of focus, and cravings: this is reactive hypoglycemia.

Conversely, a low or moderate GI meal produces a gradual and prolonged rise in blood sugar, with measured insulin secretion. The result: stable energy for 3 to 4 hours, better concentration, and an absence of cravings.

This dynamic is particularly important for people with insulin resistance, pre-diabetes, or type 2 diabetes. But even in healthy people, favoring low-GI foods improves digestive comfort and cognitive performance.

The insulin response

Insulin is the hormone that allows glucose to enter your cells. Moderate and steady secretion is normal and desirable. Problems arise when repeated insulin spikes (from a diet high in fast sugars) lead to insulin resistance over the years.

Insulin resistance is the core mechanism of metabolic syndrome and type 2 diabetes. Cells become less sensitive to insulin, and the pancreas compensates by producing more, creating a vicious cycle that promotes abdominal fat storage.

A low or moderate GI diet, combined with regular physical activity, is the most effective strategy for maintaining good insulin sensitivity. Strength training is particularly effective because it increases the muscles' ability to take up glucose.

FoodCraft Tip

GI-controlled recipes with FoodCraft

FoodCraft AI can adapt any recipe to reduce its glycemic load: substituting white rice with brown rice or quinoa, adding legumes, or replacing sugar with low-GI alternatives. You eat what you love, with a reduced glycemic impact.

Frequently asked questions

Is the glycemic index reliable?
GI is a useful but imperfect tool. It is measured on isolated foods, whereas we rarely eat a single food by itself. Additionally, glycemic response varies from person to person. Use it as a general guide, not an absolute rule, and prefer the glycemic load for a more realistic view.
Should I avoid all high-GI foods?
No. High-GI foods have their place, especially around physical exercise. Furthermore, when consumed as part of a mixed meal with proteins, fats, and fiber, their glycemic impact is significantly reduced. The key is not to base your entire diet solely on fast carbohydrates.
Does cooking change the glycemic index?
Yes, significantly. Al dente pasta has a lower GI than overcooked pasta. Cooled potatoes (in a salad) have a lower GI than hot potatoes due to the formation of resistant starch. A green banana has a lower GI than a ripe one. Cooking methods and ripeness alter the starch structure.
Is the glycemic index important if I'm not diabetic?
Yes. Even without diabetes, a diet chronically high in high-GI foods increases the risk of developing insulin resistance, promotes cravings and energy crashes, and can contribute to weight gain. Everyone benefits from making smart glycemic choices.

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