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Why refined carbs are bad for you

A close look at refined carbs, and why they are bad for your health

Refined or simple carbs are low in fiber, vitamins, and minerals. They are also linked to weight gain and many serious diseases.

This article is based on scientific evidence, written by experts, and fact-checked by experts.
We look at both sides of the argument and strive to be objective, unbiased, and honest.
Why refined carbs are bad for you
Last updated on September 15, 2023, and last reviewed by an expert on November 9, 2022.

Not all carbs are the same.

Why refined carbs are bad for you

Many whole foods that are high in carbs are incredibly healthy and nutritious.

On the other hand, refined or simple carbs have had most of the nutrients and fiber removed.

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Eating refined carbs is linked to a drastically increased risk of many diseases, including obesity, heart disease, and type 2 diabetes.

Almost every nutrition expert agrees that refined carbs should be limited.

However, they are still the primary source of dietary carbs in many countries.

This article explains what refined carbs are and why they harm your health.

What are refined carbs?

Refined carbs are also known as simple carbs or processed carbs.

There are two main types:

Refined carbs have been stripped of almost all fiber, vitamins, and minerals. For this reason, they can be considered “empty” calories.

They are also digested quickly and have a high glycemic index. This means that they lead to rapid spikes in blood sugar and insulin levels after meals.

Eating foods high on the glycemic index has been linked to overeating and increased risk of many diseases.

Sadly, sugars and refined grains are a very large part of the total carbohydrate intake in many countries.

The primary dietary sources of refined carbs are white flour, white bread, white rice, pastries, sodas, snacks, pasta, sweets, breakfast cereals, and added sugars.

They are also added to all sorts of processed foods.

Summary: Refined carbs include mostly sugars and processed grains. They are empty calories and lead to rapid blood sugar and insulin spikes.

Refined grains are much lower in fiber and micronutrients

Whole grains are very high in dietary fiber.

They consist of three main parts:

  1. Bran: The hard outer layer containing fiber, minerals, and antioxidants.
  2. Germ: The nutrient-rich core contains carbs, fat, protein, vitamins, minerals, antioxidants, and plant compounds.
  3. Endosperm: The middle layer, mainly containing carbs and small amounts of protein.

The bran and germ are the most nutritious parts of whole grains.

They contain high amounts of many nutrients, such as fiber, B vitamins, iron, magnesium, phosphorus, manganese, and selenium.

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The bran and germ are removed during the refining process, along with all the nutrients they contain.

This leaves almost no fiber, vitamins, or minerals in refined grains. The only thing left is rapidly digested starch with small amounts of protein.

That being said, some producers enrich their products with synthetic vitamins to compensate for the loss in nutrients.

Whether or not synthetic vitamins are as good as natural vitamins has long been debated. However, most people will agree that getting your nutrients from whole foods is always the best choice.

Diets high in refined carbs also tend to be low in fiber. Low-fiber diets have been linked with an increased risk of diseases like heart disease, obesity, type 2 diabetes, colon cancer and various digestive problems.

Summary: When grains are refined, almost all the fiber, vitamins, and minerals are removed. Some producers enrich their products with synthetic vitamins after processing.

Refined carbs can drive overeating and increase the risk of obesity

A large portion of the population is overweight or obese. Eating too many refined carbs may be one of the main culprits.

Because they are low in fiber and digested quickly, eating refined carbs can cause significant swings in blood sugar levels. This can contribute to overeating.

This is because foods high on the glycemic index promote short-term fullness, lasting about one hour. On the other hand, foods low on the glycemic index promote a sustained feeling of fullness, which lasts about two to three hours.

Blood sugar levels drop about an hour or two after eating a meal high in refined carbs. This promotes hunger and stimulates parts of the brain associated with reward and craving.

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These signals make you crave more food and are known to cause overeating.

Long-term studies have also shown that eating refined carbs is linked with increased belly fat over the course of five years.

Furthermore, refined carbs may cause inflammation in the body. Several experts have speculated that this may be one of the primary dietary causes of leptin resistance and obesity.

Summary: Refined carbs cause rapid spikes in blood sugar and insulin levels and only make you feel full for a short time. This is followed by a drop in blood sugar, hunger, and cravings.

Refined carbs may increase the risk of heart disease and type 2 diabetes

Heart disease is incredibly common and currently the world’s biggest killer.

Type 2 diabetes is another very common disease, affecting about 300 million people worldwide.

People with type 2 diabetes have a high risk of developing heart disease.

Studies show that high consumption of refined carbs is linked with insulin resistance and high blood sugar levels. These are some of the main symptoms of type 2 diabetes.

Refined carbs also increase blood triglyceride levels. This is a risk factor for both heart disease and type 2 diabetes.

One study in Chinese adults showed that over 85% of the total carbohydrate intake came from refined carbs, mainly white rice and refined wheat products.

The study also showed that people who ate the most refined carbs were two to three times more likely to get heart disease than those who ate the least.

Summary: Refined carbs may increase blood triglycerides, blood sugar levels and cause insulin resistance. These are major risk factors for heart disease and type 2 diabetes.

Not all carbs are bad

Eating a lot of refined carbs can have many adverse health effects. However, not all carbs are bad.

Some carbohydrate-rich, whole foods are incredibly healthy. These are excellent sources of fiber, vitamins, minerals, and beneficial plant compounds.

Healthy carb-rich foods include vegetables, fruit, legumes, root vegetables, and whole grains, such as oats and barley.

Unless you are following a carb-restricted diet, there is no reason to avoid these foods just because they contain carbs.

Here is a list of 12 high-carb foods that are incredibly healthy:

12 high carb foods that are incredibly healthy
Suggested read: 12 high carb foods that are incredibly healthy

Summary: Whole foods containing carbs are incredibly healthy. These include vegetables, fruits, legumes, root vegetables, and whole grains.


For optimal health (and weight), try to get most of your carbs from whole, single-ingredient foods.

A food with a long list of ingredients is probably not a healthy carb source.

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