Foods, Prediabetes

What Is a Refined Carbohydrate?

It is important to understand that the type of carbohydrates you choose to consume makes a very big difference in how it affects your health.
What Is a Refined Carbohydrate?
Chelsea Clark

A carbohydrate is a type of nutrient made up of sugar molecules linked together, says the Cleveland Clinic. Carbohydrates are found in a wide variety of foods that we eat every single day, from hamburger buns to cupcakes to oats to beans to carrots to apples.

It is important to understand that the type of carbohydrates you choose to consume makes a very big difference in how it affects your health. As the American Heart Association explains, not all carbs are created equal.[1] One type of carbohydrate that can be detrimental to your health is called a refined carbohydrate.

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If you have a health condition like prediabetes, staying away from refined carbohydrates is an important step in getting your health back on track.

What is a refined carbohydrate?

A refined carbohydrate is a carbohydrate that has undergone heavy processing and that has been stripped of fiber, vitamins, minerals, and other nutrients. A whole grain like wheat can be refined, for example, by milling it to remove the germ and bran, grinding it up into small pieces, and creating an end product of white flour. White flour is considered a refined carbohydrate.[1,2]

Pre-packaged and highly-processed foods tend to be high in refined carbohydrates. Examples of refined carbohydrate foods include white bread, pasta, white rice, crackers, pastries, cupcakes, cookies, cake, and many breakfast cereals.[1,2]

Whole-food sources of carbohydrates that still resemble their original, natural form are different. Carbohydrates like those found in whole grains, vegetables, legumes, and fruits are usually intact and they come along with other important nutrients like vitamins, minerals, and fiber. These foods still contain natural carbohydrates, but they are more nutrient rich and the carbohydrates are digested more slowly by the body.[1,2]

How refined carbohydrates affect blood sugars

All carbohydrates are made up of sugar molecules linked together. So when we digest them, they are broken down into sugar. Depending on what type of carbohydrate we consume, that can affect our blood sugar to varying degrees.

When grains are refined, it basically leaves a simple carbohydrate product behind – one that can be quickly broken down by the body to form sugar. When we eat a refined carbohydrate, it will lead to rapid and large spikes in blood sugar levels

Refined carbohydrates that have been highly processed are high on the glycemic index, which is a measure of how much a food affects your blood glucose levels. Unfortunately, eating refined carbohydrates high on the glycemic index is linked to chronic conditions like diabetes, heart disease, and obesity.[3]

Minimally processed carbohydrates like whole grains, on the other hand, still contain fiber and other nutrients, and they are more intact. The body digests these kinds of carbohydrates more slowly which leads to smaller, slower blood sugar responses.[2]

If you have prediabetes, you will want to minimize swings in blood sugar – which makes complex carbohydrates in foods like whole grains much more preferable over refined carbohydrates.

Refined carbohydrates and prediabetes: a dangerous combination

Because refined carbohydrates are broken down so rapidly in the body and can spike your blood sugar levels, they are not a healthy choice for people with prediabetes. When you have prediabetes, your body is not able to process blood sugar swings like it is supposed to.

Normally, when you digest carbohydrate foods and release sugar into your bloodstream, your body is able to take that sugar out of your blood and use it for energy. It uses the hormone insulin to do this, which lowers your blood sugar levels back to where they need to be.[3]

But if you have prediabetes, insulin is no longer functioning the way it should be and your body is having trouble moving sugar from your blood and into your cells. When you eat foods that spike your blood sugar, like refined carbohydrates with a high glycemic index, your body isn’t able to keep up. Over time, this can become quite harmful and can pave the way for a type 2 diabetes diagnosis.[1,3]

Whole grains and less processed forms of carbs put less stress on your body’s system and its reliance on insulin, which can help you to avoid type 2 diabetes.

Another reason refined carbs can be bad for prediabetes is that they don’t keep you feeling full for very long. They are digested quickly and can leave you hungry soon after eating them. This can pose a problem when it comes to avoiding overeating and maintaining a healthy weight, both of which are important to reduce diabetes risk.[1]

There’s a robust body of scientific evidence to support the link between refined carbohydrates and diabetes. Studies show that eating refined carbohydrates (along with sugars and starchy foods) can increase your type 2 diabetes risk, while eating minimally processed whole grains can actually decrease your risk.[4,5,6]

The authors of one major study looking at data from over 200,000 people conclude that their findings “highlight the importance of making a distinction between carbohydrates from high and low quality sources.”[4]

Replacing refined carbohydrates with healthier choices

We don’t have to banish carbs completely from our diets to get healthy and reduce our risk of diseases like diabetes. But we do need to be careful about what kinds we consume, choosing high-quality unprocessed carbs rather than low-quality refined ones.

When looking at carbs, both the American Diabetes Association and the American Heart Association recommend the following:

  • Limit refined, highly-processed carbohydrate foods (especially those with added sugars) like sugary cereals, snack foods, white bread, sodas, pastries, and more.
  • Choose less processed carbohydrates like those found in vegetables, fruits, legumes, and whole grains.[1,2]

Research shows that replacing refined carbohydrates with healthier food options can reduce your type 2 diabetes risk, along with the risk of serious complications that can come along with diabetes.[7]

Refined carbohydrates to avoid

  • White bread
  • White rice
  • Cereals like cornflakes and sugar-sweetened cereals
  • Instant oats
  • French fries
  • Baked goods
  • Pastries
  • White flour pasta·  Flour tortillas

Healthier alternatives to eat more of


Your total carb intake isn’t as important as the type of carbohydrates you consume when it comes to chronic disease risk.[5] One type of carbohydrate that is important to stay away from is refined carbohydrates – especially if you have prediabetes.

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Researchers believe that the more we swap out refined carbohydrates for unprocessed carbohydrates, the better off we will be.[5]

The key is to choose carbohydrates low on the glycemic index that are as minimally processed as possible. Go for high fiber foods that are rich in other nutrients like protein, healthy fat, vitamins, and minerals. Whole grains, vegetables, legumes, and more are all good choices.

Curious to learn more about the best and worst carbs for prediabetes? Go here!