Carbohydrates are one of three macronutrients — alongside fat and protein — and they’re your body’s primary energy source.
When you eat carbs, your body breaks them down into simple sugar molecules, mainly glucose. These sugar molecules enter your bloodstream and serve as energy for your cells.
Refined carbohydrates are carbs that have had most of their nutrients removed during processing.
Research indicates that diets with large amounts of refined carbs aren’t good for metabolic, heart, brain, or mental health. Still, the average Western diet includes an excessive amount of refined carbs.
In this article, we’ll explore how refined carbs affect your body and overall health. We’ll also look at some common sources of these carbs and describe how to swap them for more nutrient-dense options.
ZOE runs the largest nutrition science study in the world, with more than 50,000 participants so far. We’ve found that how your body responds to refined carbs is unique to you.
With ZOE's personalized nutrition program, you can learn how your body responds to foods and how to eat for your long-term health.
Different types of carbs
There are three types of carbohydrates — simple carbs, starches, and fiber. Many whole foods contain a mix.
Simple carbs are made from one or two sugar molecules. These sugars can reach your bloodstream quickly, and your cells then take them up for energy.
Because it doesn’t take very long to digest simple carbs, eating foods that contain lots of these sugars can lead to spikes in blood sugar levels in some people.
A lot of foods that aren’t very nutritious, like sugary drinks and candies, are high in simple carbs, mostly in the form of added refined sugars, like table sugar and high-fructose corn syrup.
Some healthy foods — like whole fruits, milk, and other dairy products — naturally contain simple carbs, along with many other important nutrients.
Because these simple carbs are naturally present in the complex structure of the food, they’re less likely to cause big rises in blood sugar.
Starches, like fiber, are a type of complex carbohydrate.
As you might expect, complex carbs have a more complicated structure than simple carbs. This means that it takes your body longer to break them down into smaller sugars and absorb them.
Since this process takes longer, you typically end up with a more gradual rise in blood sugar than you get with simple carbohydrates.
Whether a starchy food is more or less nutritious depends on how much processing or refining it undergoes.
Whole grains are a type of whole starchy food and are good for your health. White bread made with refined white flour, on the other hand, is a type of refined, starchy food. It’s a less healthy option because it lacks many useful nutrients.
Good sources of healthy starches include:
whole grains, such as oats, barley, brown rice, and quinoa
legumes, such as beans and lentils
vegetables, such as potatoes, broccoli, and spinach
nuts and seeds, such as almonds, walnuts, sunflower seeds, and pumpkin seeds
Fiber is another type of complex carbohydrate. But unlike starches, your body can’t digest it.
Although it doesn’t directly provide energy, fiber is incredibly important for your overall health. It promotes regular bowel movements and is beneficial for your gut health.
Some fiber also acts as food for the trillions of microbes living in your gut, collectively called the gut microbiome.
How to swap out refined carbs
Swapping out refined carbs for unrefined carbs can be a great way to promote your overall health.
Researchers have associated a higher intake of whole grains — but not refined grains — with better blood sugar control, body weight, and fat distribution.
Here are some quick swaps you can try to build a more nutrient-dense diet.
|Source of refined carbs||Food swap|
|white bread||wholegrain bread|
|white rice||brown rice, cauliflower rice, quinoa|
|most pastas||wholegrain pastas|
|sugary drinks||herbal teas|
|ultra-processed snacks, like potato chips||nuts, like almonds and cashews|
|candies||berries, dark chocolate|
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What does ‘refined’ mean?
“Refined” carbs have been through a manufacturing process that has removed many of their health-promoting nutrients and compounds.
Carbs are made up of sugars, but they can also contain fiber, vitamins, minerals, and polyphenols. The manufacturing, or refining, process removes these.
For example, whole grains, like wheat, have three main parts: the bran, endosperm, and germ.
The bran and germ contain plenty of vitamins, minerals, antioxidants, fiber, and other healthful compounds. The endosperm is easily digestible, but it contains fewer nutrients.
Health impacts of refined carbs
Eating too many refined carbs isn’t good for your health. Still, refined carbs make up a large part of the average Western diet.
Research suggests that diets high in refined carbs may increase the risk of many health conditions, including those relating to:
metabolic health, such as obesity, type 2 diabetes, and insulin resistance
brain health, such as dementia and Alzheimer’s disease
Blood sugar spikes
When you eat refined carbs, your body breaks them down quickly into simple sugars, leading to a rise in your blood sugar level.
A blood sugar increase after you eat is normal. But if your blood sugar is frequently very high, this can lead to chronic health conditions, like prediabetes and type 2 diabetes.
There are three main types of carbohydrates: simple carbs, starches, and fiber.
Carbs are an important energy source, but the quality of your carb-containing foods is key when it comes to your long-term health.
Refined carbohydrates have gone through a manufacturing process that removes most of their nutritional value. This means you can lose out on fiber, vitamins, minerals, and polyphenols.
Some common sources of refined carbs include white bread, white rice, and ultra-processed snacks, like potato chips and candy.
Swapping out some refined carbs for unrefined versions can make a big difference in your diet.
For many people, eating refined carbs is likely to lead to large blood sugar rises, but each person’s response is unique.
With the ZOE at-home test, you can learn about your own blood sugar and blood fat responses, as well as which “good” and “bad” bugs are living in your gut.
Are refined carbohydrates worse than saturated fat? The American Journal of Clinical Nutrition. (2010). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2869506/
Association between sugar-sweetened beverages and type 2 diabetes: A meta-analysis. Journal of Diabetes Investigation. (2014). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420570/
Composition and functionality of wheat bran and its application in some cereal food products. International Journal of Food Science & Technology. (2015). https://ifst.onlinelibrary.wiley.com/doi/10.1111/ijfs.12935
Death by carbs: Added sugars and refined carbohydrates cause diabetes and cardiovascular disease in Asian Indians. Missouri Medicine. (2016). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6139832/
Dietary fibre from whole grains and their benefits on metabolic health. Nutrients. (2020). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7599874/
High glycemic index diet as a risk factor for depression: Analyses from the Women’s Health Initiative. The American Journal of Clinical Nutrition. (2015). https://academic.oup.com/ajcn/article/102/2/454/4564524
Human postprandial responses to food and potential for precision nutrition. Nature Medicine. (2020). https://www.nature.com/articles/s41591-020-0934-0
Intake of refined carbohydrates and whole grain foods in relation to risk of type 2 diabetes mellitus and coronary heart disease. Journal of the American College of Nutrition. (2002). https://pubmed.ncbi.nlm.nih.gov/12166526/
Refined carbohydrate-rich diet is associated with long-term risk of dementia and Alzheimer's disease in apolipoprotein E ε4 allele carriers. Alzheimer’s & Dementia. (2020). https://alz-journals.onlinelibrary.wiley.com/doi/10.1002/alz.12114
Refined carbohydrates, phenotypic plasticity and the obesity epidemic. Medical Hypotheses. (2019). https://www.sciencedirect.com/science/article/pii/S0306987719306462
SACN Carbohydrates and Health Report. (2015). https://www.gov.uk/government/publications/sacn-carbohydrates-and-health-report
Sugar-sweetened beverages and cardiometabolic health: An update of the evidence. Nutrients. (2019). https://www.mdpi.com/2072-6643/11/8/1840
The carbohydrate advantage. (n.d.). https://www.pcrm.org/good-nutrition/nutrition-information/the-carbohydrate-advantage
The impact of Western diet and nutrients on the microbiota and immune response at mucosal interfaces. Frontiers in Immunology. (2017). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5532387/
Whole grains. (n.d.). https://www.hsph.harvard.edu/nutritionsource/what-should-you-eat/whole-grains/