What the different types of carbs are and how they can affect your health

• Carbs are made up of sugar molecules. But not all of these molecules look the same. They link together in different configurations that form the three main types of carbohydrates: sugar, starch, fiber.
• Simple carbs like sugar can quickly raise your blood glucose levels while the complex carbs in whole grains may be healthier, because they don't spike blood glucose levels.
• Carb-rich foods can have a different effect on your body depending on how they are cooked or processed.
• This article was reviewed by Melissa Rifkin, MS, RD, CDN, owner of Melissa Rifkin Nutrition LLC.

Carbs often get blamed for weight gain. But what are carbohydrates? And are they really a detriment to our health?

The truth is that we need carbs to fuel our bodies. But not all carbs are created equal and problems come up when we eat too many simple carbs compared to complex carbs. Medical professionals may recommend that those with type 1 or 2 diabetes reduce their simple carb intake.

For most healthy people, however, carbs — both simple and complex — are a vital part of a balanced diet, providing energy and nutrients. Here's what you need to know about carbs and your health.

Carbs are made up of sugar

Merriam-Webster defines a carbohydrate as "any of various neutral compounds of carbon, hydrogen, and oxygen (such as sugars, starches, and celluloses) most of which are formed by green plants and which constitute a major class of animal foods."

Put more simply, carbohydrates are made up of sugar molecules. But not all of these molecules look the same. They link together in different configurations that form the three main types of carbohydrates:

• Sugar, which can be found in fruits, vegetables, table sugar, and dairy products.
• Starch, which can be found in vegetables, grains, and beans.
• Fiber, which can be found in fruits, vegetables, whole grains, and beans.

As you can see, some foods like vegetables have all three types of carbohydrates whereas dairy only has one — sugar. And what types of carbs are in your food can tell you a lot about how your body will react to them.

When you eat sugar or starch, for example, your digestive system breaks it down into glucose, the blood sugar that normally fuels all of your body's processes. Fiber, on the other hand, is broken down in the small intestine, mostly unchanged until it meets the large intestine. We need all three types of carbohydrates for a balanced, nutritional diet.

Plants create carbs, animals eat them

Check out nutrition labels in your local market and you'll find that most of the carbohydrates in our diet come from plants like fruits, vegetables, and grains, while we get very few carbs from eating meat. This is because animals don't make their own carbs. Rather, they rely on getting them from plants in their diet.

Plants, on the other hand, create their own carbohydrates, which provide plants with energy to grow and reproduce, says Joshua Lambert, a professor of food science at Penn State University. So, when we eat those plants we get a similar energy boost.

How our bodies process carbs

Since our bodies break sugars and starches down into glucose, foods high in these types of carbohydrates elevate the glucose in our blood — also known as our blood sugar levels. So logically speaking, the more sugar and starch in your food, the more it will increase your blood sugar levels. But that's not always the case because how those carbs are structured in the food also plays a role.

The process of cooking can change the structure of those carbs, which affects how quickly you digest your food. For example, if you eat a raw potato, the starch molecules are packed closely together, so it takes longer for your body to break down the starches and digest them. Because your body does not absorb the starch quickly, you should not see a big spike in your blood sugar.

When you boil a potato, the starches relax apart, making them easier to digest. Your small intestine will absorb the starches more quickly, which can cause a rise in your blood sugar.

However, if you let your cooked potato cool off and make a cold potato salad, the starches will reverse this process, becoming denser and slower to digest once again.

In moderation, there are no "good" or "bad" carbs

"There is no such thing as good carbs and bad carbs," Lambert says. Instead, the main difference between carbs is how easily and quickly we digest them.

• Simple carbs are carbs that have often been processed in some way, like the sugars in fruit juice or starches in white bread. Their structure makes them quick and easy to digest and since many processed foods are high in these types of carbs, they run the risk of spiking your blood sugar levels. Too many of these simple carbs are linked to health issues like obesity and type 2 diabetes.
• Complex carbs tend to be unrefined and retain the fiber that naturally occurs in food, which means we digest them more slowly and as a result, they are less likely to spike blood sugar levels. Complex carbs can be found in vegetables and whole grains like brown rice.

Though it is healthier to eat more complex carbs, "all of these carbs are useful to our bodies," Lambert says. Adding that it's okay to eat some sugar, but the important thing is to eat all carbs in moderation.

People with type 1 or 2 diabetes may need to cut down on simple carbohydrates and should be cautious about their sugar intake. However, Lambert says, "for most healthy, active people, carbs (both simple and complex) are an important part of a balanced diet."

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