CARBOHYDRATES—Good for the Body, Necessary for the Brain

More often than not, at least in the fad diet world, carbohydrates—aka carbs— get a bad rap for being unhealthy. Unfortunately, the abounding misinformation about carbs has created ambiguity in the public’s eye regarding their true nutritional worth. Carbohydrates are, in fact, one of the main macronutrients the body needs to maintain proper health.1 Carbs are the body’s preferred energy source, and whole, plant-based foods containing complex carbohydrates offer the body a variety of vitamins, minerals, fiber, and other nutrients.2 Carbohydrates play an especially important role in brain health.


Carbohydrates are a macronutrient that your body breaks down into glucose, a type of sugar. Carbs are found in a wide array of foods and in a variety of forms, including sugar, starch, and fiber.3

Sugar. Intrinsic sugars are those that occur naturally in foods, primarily whole fruits and vegetables. These sugars are considered intrinsic because they are natually enclosed within the cells of the food. Sugars that are added to foods during processing and preparation are considered extrinsic sugars. These sugars are considered extrinsic because they are not located within the cellular structure of the food.  Extrinsic sugars are used to sweeten the flavor of foods and beverages and improve their palatability.4 Sugar, in and of itself, provides energy (i.e., calories) but insignificant amounts of vitamins, minerals, or other essential nutrients; however, whole fruits and vegetables, despite their naturally occurring sugar content, are great sources of nutrients, whereas processed foods with added sugar often have had the nutrients stripped away during processing, so, unlike fruits and vegetables, you’ll get a lot of calories without the benefit of actual nutrition.

Starches. Starches comprise many glucose units that are linked together.4 Bread and pasta may come to mind when you think of starches, but starches are also found in whole grains (e.g., oats, rice), cooked potatoes, and legumes and beans.5 Most starches (e.g., those from processed food sources) are broken down into sugars by digestive enzymes in the body; however, some starches are resistant to these digestive enzymes (e.g., those from whole grains), providing fuel for the beneficial bacteria that reside in our gastrointestinal tract and helping to regulate blood sugar.

Fiber. Like starches, fiber is mostly made of sugar units that have bonded together, but in the case of fiber, these bonded units cannot be broken down by digestive enzymes.4 There are two main types of fiber: dietary fiber, which is naturally occurring and only found in plants, and functional fiber, which comprises isolated fibers that can be added to foods and have positive physiologic effects.1


The brain is arguably the busiest organ in the body—it continually monitors, regulates, and powers the body’s autonomic functioning, such as breathing, heart beat, and digestion, even when we sleep. Simultaneously, the brain also empowers us to make decisions, learn, read, speak, remember, and accomplish dozens of other tasks throughout the day. Like the rest of the body, the brain needs energy to do all of these things. That’s where carbohydrates come in.

According to the U.S. Food and Drug Administration (FDA), the human body needs approximately 275 grams of carbohydrates per day.6 This sounds simple, but not all carbs are created equal. In addition to the three common forms (e.g., sugars, starches, fibers), carbs are divded into two main categories: simple and complex.­4

Simple carbs. When you think of simple carbohydrates, think “simple nutrition.” Simple carbs are sugars or, if you prefer, sugars are simple carbs, and these include both intrinic sugars (e.g., the naturally occurring sugars in fruits, vegetables, and milk) and extrinsic sugars (e.g., the refined sugars added to food, such as raw and brown sugar, corns syrups, and fruit juice concentrates).3

Complex carbs. Complex carbs, as their name suggests, pack in more nutrients than simple carbs. Starch and fiber are considered complex carbs. Fiber and enzyme-resistant starches are digested slowly, which promotes satiety and is conducive to weight loss.3,4 Sources of complex carbs include whole grains, fiber-rich fruits and vegetables, and beans.


It’s common to only think of carbohydrates as fuel for physical performance. You’ve probably heard of athletes “carb loading” the night before a race or competition. However, carbs are just as important, if not more so, to your brain. In fact, the brain actually consumes an immense amount of energy relative to the rest of the body,8 and this energy comes from the glucose the body has converted from carbohydrates. Many studies have found a positive relationship between carbohydrate consumption and cognition; the fewer carbs you eat, the more likely you are to have “brain fog,” feel confused, and be less vigilant.9


Carbohydrates are a critical source of energy for the body, especially the brain. There are two main categories of carbs—simple and complex—of which there are three main forms—sugar, starch, and fiber. Following a well-balanced diet, part of which includes consuming complex carbohydates in the form of whole-food, plant-based food sources, in addition to getting plenty sleep and staying physical active, is more likely to lead to better overall health, an optimal body weight, and a clear head than attempting to eliminate carbohydrates from your diet for the sake of weight loss.


1.   Behavioral Nutrition website. What are carbohydrates and why we need them in our diet. 25 Feb 2020. Accessed 14 Jun 2021.

2.  Ellis E. Carbohydrates—part of a healthful diabetes diet. 16 Nov 2020. EatRight website. https:/ Accessed 15 Jun 2021.

3.  Harvard T.H. Chan School of Public Health website. Carbohydrates. Accessed 14 Jun 2021.

4.  Slavin J, Carlson J. Carbohydrates. Adv Nutr. 2014;5(6):760-761. Published 2014 Nov 14.

5.  Ask the Expert: Legumes and Resistant Starch. Harvard T.H. Chan School of Public Health website. Accessed 15 Jun 2021.

6.  FDA. Mar 2020. Total Carbohydrate. U.S. Federal Drug Administration website. Accessed 15 Jun 2021.

7.  Bridges M, Zieve D, Conaway B. Updated 8 Aug 2020. Complex carbohydrates. MedLine Plus (U.S. National Library of Medicine) website. Accessed 21 Jun 2021.

8.  Gómez-Pinilla F. Brain foods: the effects of nutrients on brain function. Nat Rev Neurosci. 2008;9(7):568-

9.         D’Anci KE, Watts LR, Kanarek RB, Taylor HA. Low-carbohydrate weight-loss diets. Effects on cognition and mood. Appetite. 2009;52(1):96-103.

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