Just like protein composition, carbohydrate composition can refer to several concepts. The most common is the glycemic index, which we already talked about in the lesson on the different types of carbs. I will explain the concept of the glycemic index again in this lesson, because it is the most well known measure of carbohydrate composition. If you already understood it, or you don't want to hear it again, you can skip this lesson though. In its simplest form, the glycemic index is a measure of both how fast food raises your blood glucose levels, and how much it elevates insulin levels. The measure is generally applied to carbohydrates and range from zero to 100.
The faster a carb is absorbed, and the larger its effect on insulin, the closer it will be to 100. Slower absorbing and digesting carbs, on the other hand will be closer to zero. Here's a short list of common carbs and their gi rankings. As you can see, not suddenly goons have the lowest GIS Fruits and milk products are a bit better. Whole grains are in the middle range. Processed carbs are on the high end and sugary cereals and Gatorade topped the list.
Now, just as with protein quality, the glycemic index comes with a big bud. And here's the problem. Gi rankings are based on the glycemic effect of specific foods that are consumed isolated and in a fasted state. That means unless you eat first thing in the morning, or after a long fast, you will never be consuming your carbohydrates in a fasted state. And even then, a typical fitness meal plan always combines carbohydrates with fats and proteins. And since fiber and fat, slow digestion and absorption, they have a lowering effect on the glycemic index of any congested carbs.
What's more, is that even in the rare case that you did consume a high glycemic carbohydrate source alone in a fasted state. It still won't affect you to any meaningful degree unless you have a pre existing health condition that you human body is very good at keeping your blood sugar level and insulin levels within a fairly precise range. This applies especially to people who regularly exercise. What this means is that even though the GI index is a nice theoretic concept in real world scenarios, it's really not as important as many people make it out to be. Having your blood sugar or insulin level increased to higher than normal rates isn't going to have any measurable impact on your muscle building or fat burning goals. Instead of comparing past carbs and slow carbs, here's what you should focus on.
First, get the majority of your carb intake from high fiber minimally processed sources. This includes foods such as oatmeal, rice, both brown and white rice, potatoes, whole grain pasta fruits and vegetables. Second, consume your carbs as part of a complete meal with protein and healthy fats. As long as you do these two things, you're good as gold and there is no need to go crazy about carb composition.