Introduction to the Glycemic Index

In a previous section we covered carbohydrates and the effect they have on the body after they are consumed. Now we are going to go a step further and I am going to explain to you how all carbohydrates are not created equal. I base my entire diet around this information, and this is particularly important for you to understand in order to fine-tune your diet for optimal results. This tool is called the glycemic index.

What is the Glycemic Index?

The glycemic index (GI) is a system of assigning a number to carbohydrates to show how quickly each one increases blood sugar. In simple terms, carbohydrates are all broken down into glucose; but the speed at which that happens varies for different foods. This is measured on a scale of 0-100, with glucose being at the extreme high end with a numerical rating of 100.

What this means is that if you ingested straight glucose, you would have an almost instant spike in blood glucose levels throughout the body. The body does not have to break it down and it passes through the digestive system into the bloodstream very quickly.

On the other end of the scale, we have vegetables such as broccoli with a rating of 15. Broccoli has fiber which slows down digestion, causing a gradual rise in blood sugar instead of a large spike like we had with glucose.

If you look at brown rice, it has an average GI rating of 50. This is due to the brown fiber that encases the rice grain, which slows down digestion. White rice is the exact same, but they have stripped away the outer coating. The effect of doing this is that digestion is sped up, and the GI rating is now around 72!

Another interesting fact is that in a food such as a banana, the glycemic rating actually goes up the more it ripens. A banana that is greenish-yellow in color is lower on the scale than a banana that starts to get black spots on it. I am sure you have eaten both varieties, and the more ripened banana is much sweeter. So generally, the sweeter a food is, the higher it is on the glycemic index.

You should double check to verify, because with modern day artificial sweeteners, they have been able to make foods extremely sweet without using high-glycemic processed sugars. I covered sugar in its own section due to the importance of knowing how to track it in your diet.

Glycemic Load: Quantity Matters Too

You can download any glycemic index chart online to find out which foods are low, moderate, or high GI rated. However, there is something else to consider, and that is the glycemic load. The glycemic load is a better estimation of how much as well as how quickly glucose is going to be converted from any carbohydrate.

For example, a serving of watermelon has a GI rating of 80, which means it will break down in the body very quickly into glucose. But the amount of carbohydrates in a serving of watermelon is so small that it has a very small glycemic load rating.

Think of glycemic index as the “quality” of a carbohydrate and the glycemic load as the “quantity.”

For example, let’s say you are having pasta for dinner, which has a low to moderate glycemic rating of around 55. The glycemic load of a small plate of pasta vs a large plate of pasta will be much different due to the amount of carbohydrates you are consuming. Even though the glycemic index of the pasta is the same for both plates, the amount of glucose your body is going to get after digestion from each serving is different.

Another interesting fact about glycemic load is what happens when you combine foods together like we do in most meals. When you add protein such as chicken, or especially a vegetable with a lot of fiber, they slow down digestion and thus lower the overall glycemic index of the meal, or how quickly those carbohydrates are converted to glucose.

Why Glycemic Index and Load Matter

You might be wondering why the glycemic index and glycemic load are important when choosing what carbohydrates you plan to eat throughout the day. It comes down to a hormone we talked about in a previous section, which is insulin. High glycemic index carbohydrates cause a large release of insulin due to the quick spike in blood sugar.

There are certain times that we want a large insulin spike, and other times when we want to keep insulin in check. I am sure you have heard the terms simple and complex carbohydrates. Complex carbohydrates are unprocessed foods such as vegetables and grains. Simple carbohydrates are usually processed foods with high sugar content.

Complex carbohydrates are generally healthier and are on the low to moderate GI scale. Simple carbohydrates tend to be on the moderate to high end of the scale. If you consume a complex carbohydrate like a bowl of oatmeal, it will provide a long-steady release of blood sugar due to the fiber slowing down the digestion process. This means it will give us sustained energy over many hours, thus keeping insulin in check.

The Glycemic Index and Diabetes

Diabetics must plan meals around the glycemic index chart because their body cannot regulate blood sugar efficiently. After meals they have to check their blood sugar, usually through a prick on a finger, to make sure glucose levels are in a safe range.

If they eat a meal that has a high glycemic index or load, blood sugar may rise too quickly and they have to inject insulin to shuttle the glucose out of the blood, because in most cases their pancreas can’t secrete enough of the hormone, or the body is too insulin resistant to have an effect.

On the other hand, they also must monitor if their blood sugar gets too low. Low blood sugar can lead to dizziness, confusion and even coma, so when that happens, they must ingest a high-glycemic food such as gummy bears or glucose tablets to bring blood sugar levels back up quickly.