Differences Between Simple and Complex Carbs

There is conflicting information out there about carbohydrate-laden foods. Studies have shown that low-carb diets are effective for weight loss, but that doesn’t mean that eating carbs automatically leads to obesity. In fact, there are plenty of health benefits associated with eating carbohydrates, but only if you eat the right kinds. While some high-carb foods are highly nutritious and even helpful for weight management, others are detrimental to your health.

What are carbs?

Carbohydrates (Carbs) are one of three macronutrients that provide the body with energy. The other two are protein and fat.

There are three major classes of carbs:

  • Sugars: Individual sugar molecules or short chains of sugar molecules. These include glucose, fructose, galactose and sucrose
  • Starches: Longer chains of carbohydrate molecules that need to be broken down in the digestive system.
  • Fiber: Carbohydrates that the body cannot digest

The primary function of carbohydrates is to provide the body with energy. Most carbs are broken down into glucose in the digestive system and provide the body with fuel to perform essential functions. Each gram of carbs provides the body with four calories.The exception to this is fiber, which generally does not provide many calories.

Not All Carbs Are Created Equal

Part of the reason there is so much confusion regarding carbs is that not all carbs are created equal. People tend to classify all carbs as either good or bad, but this doesn’t make sense. There are major differences in the health effects of different types of carbs, so they cannot all be lumped into one group.  One way that carbs are classified is by the terms “simple” and “complex.” Some people define all starch and fiber as complex carbs and all sugars as simple carbs. This definition, however, can be confusing. Some starchy foods like sweet potatoes, quinoa and legumes provide many health benefits, while other starch sources like refined wheat flour are associated with a myriad of health problems. Additionally, not all sugars may have the same effect on your body. Added sugars like those found in baked goods and sugary drinks can harm your health.  The natural sugars found in whole fruits and vegetables, however, do not always have the same negative effects.

It makes more sense to define complex and simple carbs this way:

  • Complex carbs: Carbs found in whole, unprocessed foods, including fruits, vegetables, legumes and whole grains. These are highly nutritious.
  • Simple carbs: Sugars and starches that have been refined and stripped of their natural fiber and nutrients. These have little nutritional value.

Whole Grain Carbs vs. Refined (White Grain) Carbs

Complex carbs are healthier than simple carbs because they are generally nutrient dense. This means they contain a large amount of nutrients in relation to the number of calories they provide.  Whole grains, fruits, vegetables and legumes are highly nutritious foods that are rich in antioxidants, fiber, vitamins and minerals.  On the contrary, simple carbs contain “empty” calories, meaning they have calories, but very little nutritional value.

To highlight the nutritional differences between complex and simple carbs, let’s compare whole grains and refined grains.

A whole grain contains three distinct parts:

  • Germ: Part of the seed that is high in polyunsaturated fats and various important nutrients
  • Endosperm: The inner portion of the grain that’s mostly made up of starch
  • Bran: The hard outer portion of the grain that’s high in fiber and essential fatty acids

The germ and bran of a grain are where the majority of its nutrition is found. Interestingly, when grains are processed and refined, the highly nutritious germ and bran are removed, leaving only the starchy endosperm.  Whole wheat flour, for example,  is a source of several important nutrients, but those nutrients are lacking in “white” wheat flour that has been processed and refined. The same is true for fruits and vegetables. In their whole forms, they contain small amounts of sugar, but they are also packed with vitamins, minerals and fiber. On the other hand, processed foods and sugary beverages contain large amounts of sugar and few nutrients. These added sugars are associated with all kinds of health problems

Health benefits of complex carbs

Carbs are not essential for life, but eating the right kind may benefit your health.  Complex carbs are less likely to cause blood sugar spikes, whereas simple carbs, being digested very quickly, may cause a spike in your blood sugar.  The blood sugar spike stimulates your pancreas to release a large dose of insulin which often leads to a blood sugar “crash”.  This crash can leave you hungry and craving even more sugar.  Fiber-rich, complex carbs take much longer to break down than simple carbs. This may help keep blood sugar levels steady, as sugar reaches the bloodstream more gradually.  Also, because complex carbs are digested more slowly, they can provide sustained energy and help you feel full for longer

Complex carbs may reduce your risk of some chronic diseases

Consuming complex carbs may help lower your risk of chronic diseases, such as diabetes and heart disease. They tend to be high in dietary fiber, vitamins, minerals, antioxidants and plant compounds. All of these components play a role in disease prevention. Furthermore, studies have found that eating whole foods high in dietary fiber may lower “bad” LDL cholesterol and blood sugar levels, as well as help raise “good” HDL cholesterol.

Complex carbs promote a healthier digestive system

There are billions of “good” bacteria lining your intestines. These are known as your ‘gut microbiota’.They play a role in managing several digestive disorders and have been linked to various other aspects of health. Soluble fibers found in complex carbs feed the beneficial bacteria and increase their presence in your gut. They also help the bacteria produce nutrients, such as short-chain fatty acids, which are beneficial for digestive health.

Complex carbs may reduce inflammation

Inflammation is the body’s natural response to infection or injury.  Long-term inflammation, however,  can increase the risk of several chronic diseases.  While sugary foods and refined flours may promote inflammation, complex carbs may help reduce inflammation. Whole grains, fruits, vegetables and legumes contain fiber and plant compounds that have anti-inflammatory properties.

Simple carbs can be detrimental to your health

Excessive consumption of simple carbs like refined grains and added sugars can harm your body. Below are some of the detrimental health effects of simple carbs:

  • They can contribute to overeating: Simple carbs break down quickly and cause a blood sugar roller coaster. Studies have found that these blood sugar spikes and crashes may contribute to cravings, hunger and overeating.
  • High triglyceride levels risk: Large amounts of refined carbs can lead to elevated triglyceride levels, which can increase the risk of heart disease and type 2 diabetes.
  • Increased heart disease risk: Sugar and refined grains may increase heart disease risk. A study found those who ate the most refined grains were 2 to 3 times more likely to develop heart disease than those who ate the least amount.
  • Increased risk of type 2 diabetes: Excessive consumption of simple carbs can cause your cells to become resistant to insulin, which may greatly increase your risk of type 2 diabetes.
  • Sugar is addictive for some people: Similarly to recreational drugs, sugar causes the brain to release dopamine. For people that are prone to addiction, sugar can be highly addictive. 
  • Increased chance of becoming obese: Simple carbs affect the levels of appetite hormones, making them more likely to contribute to obesity.


The bottom line?  Carbohydrates can be a healthy part of your diet if you choose the right ones. Choose carbs found in foods that are in their whole, unprocessed form for optimum health and wellness. 

Sources Cited


By Donna Cross
Type 2 Advisor, The Diabetes App
11 November 2022

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