Have you ever felt yourself crash? Not the automobile type of crash, but the type of crash where you suddenly find yourself weak, tired, dizzy, or otherwise sluggish? This is because your blood sugar has dropped too low and your brain suddenly has too little. The way a human body would work best is if it had an IV drip of blood sugar throughout the day, because then it could respond very moderately to the intake of sugar. Unfortunately, that’s not realistic or practical, so the next best thing is to consider the glycemic index.

If you go for foods with a high glycemic index, you are choosing foods that will break down into sugar very quickly, which your body will clear out quickly with insulin. At a very basic level, this is how it works: When you eat something that has a lot of sugar in it, your body breaks it down easily, because it’s already practically sugar. Once all this sugar enters your bloodstream, your body reacts by getting insulin to clear it all out. As you know, too much sugar in your bloodstream is life-threatening. It’s called type 2 diabetes, where the pancreas can’t produce enough insulin anymore.

The glycemic index focuses on carbohydrates and their effect on your blood glucose levels. For your body, it’s ideal to have something resembling an IV drip of blood sugar––something that is broken down slowly and provides a slow stream of sugar, rather than an instantaneous surge of sugar that the body needs to clear out to keep you from dying. The glycemic index specifically looks at a 50-gram portion of various foods and evaluates how it raises your blood sugar levels, in terms of quantity and speed.

All food will create some sort of glycemic response, but not all carbohydrates are created equal. On an index of 1 to 100, 100 is considered to be pure glucose. Foods that are considered high on the glycemic index are 70 or higher; moderate foods are between 56 and 69; low foods are 55 and below. Pretzels are rated 81 on the glycemic index, which means they will cause a quicker glycemic response in your body than something like broccoli, which has a rating of 15.

What this means for you is that, if you want to eat healthier and feel your best, you need to look for foods with a low glycemic index. This means that you’ll have a steady stream of blood sugar, and you’ll also feel full in between meals. Again, consider what happens when you eat something like the pretzel. After you’ve eaten it, you might find yourself hungry in only a half hour or an hour. Then, you’ll crave another high glycemic food because your body cleared out too much blood sugar, and you’ll want to make up for it with something that can give you a quick response. This is a recipe for weight gain, not weight loss.

When figuring out how best to eat, find low glycemic foods that will keep you feeling full and give your body nutrients. As long as you know how to use it, the glycemic index is your best friend when it comes to health and weight loss.