When we talk about the reaction of the blood sugar to foods, appear the glycemic index or GI. This measure shows you how quickly carbohydrates in food raise your blood sugar. Even so, here is the thing, only foods with carbohydrates have GI value.
You will not find GI number for oils, fats or meat, because they do not have carbohydrates. The scale goes from 0 to 100 and pure glucose is at the top. So, if food has score of 28 on the GI scale, it raises your blood sugar by 28% compared with the glucose standard Fructose is lower, around 25, while sucrose (mix of glucose and fructose) is around 65.
How GI and GL Change Your Blood Sugar
For sorting carbohydrates, there are three categories. Foods with high GI are 70 or more, medium GI is between 56 and 69, and low GI is 55 or less. Foods that quickly break and absorb in the body cause sharp jump of the blood sugar.
On the other hand, low GI foods release glucose slowly over time. This slow releese is usually healthier; it helps to reduce your risk of diabetes type 2 and heart diseases.
What happens with those high GI foods is quite simple. Your body converts them to sugar very quickly, which triggers big amount of insulin. When insulin stays this high, your body starts to store fat more aggressively and even can gather it in the liver.
Here it gets interesting: the GI value of food on paper is not always same as what happens on your plate. The actual result depends on the preparation, storage, ripeness and what else you eat with it. Take rice as example; depends on how you cook it and what kind you use, it can range from 48 to 92, with average around 64.
Refined white flour is usually high on the scale, but whole grains are much lower. Actually, when you combine foods, that is more important than the individual GI scores. The impact of the combination is stronger than any single ingredient.
You can lower the GI of food cooking it for less time, adding acid, fats, proteins or even a splash of vinegar. Higher content of fat in food indeed pushes its GI down.
Glycemic load offers other angle that is good to understand. While GI shows how quickly the blood sugar rises, GL measures how much it actually rises. The difference is important…
GI is based on eating 50 grams of something, but GL uses normal serving sizes. Low GL foods are 10 or less, medium GL is between 11 and 19, and high GL is 20 or more. Together, GI and GL give clearer image of what food or whole meal does to your blood glucose.
The problem with the glycemic index is that it only measures single food eaten alone, not real combinations. Some high GI foods, as carrots, watermelon and potatoes, still carry useful fibers, vitamins and minerals. Plus, folks respond differently to the same foods anyhow.