Introduction to Carbohydrates

If someone says to you, “I love carbohydrates, and I eat them all day long!” what would you assume they’re eating?

Do you picture this?

Photos of carbohydrate-rich snack foods, from left to right: potato chips, bowl of M & M's, and a pastry dusted in powdered sugar.

Figure 4.1. Examples of carbohydrate-rich snack foods.

And this?

Photos of grain-based foods, from left to right: a display of bread in a bakery, a plate of spaghetti with sauce, and a bowl of plain rice topped with herbs.

Figure 4.2. Examples of grain-based foods.

When we ask this question in class, most students describe foods like the ones above. However, carbohydrates are found not just in grains, or in sweets and processed foods, but in every food group.

In fact, carbohydrates are the most abundant nutrient (except water) in the diets of most humans around the world. Since the dawn of agriculture, human cultures have relied on staple grains, such as corn, rice, and wheat, as the foundation of their diets, and these foods are rich in carbohydrates. But fruits and vegetables, dairy products, legumes, and nuts also have naturally-occurring carbohydrates. And of course, carbohydrates are a key ingredient in desserts, sugar-sweetened beverages like sodas, and many of the packaged snack foods that are readily available and—let’s face it—can be hard to stop eating.

In other words, if someone says they eat a high carbohydrate diet, that could mean many different things. They very well could be talking about a balanced diet focused on whole foods, like this:

3 photos of whole food sources of carbohydrates, from left to right: a fruit bowl with apples, peaches, and oranges; an assortment of grains and legumes, including lentils, rice, and peanuts; and an assortment of cheeses cut into small pieces.

Figure 4.3. Examples of whole foods containing carbohydrates, including fresh fruit, legumes and grains, and cheese.

The diet industry likes to sell us simple messages about “good” and “bad” foods, and these days, we tend to hear that carbohydrates are in the “bad” group. But given that carbohydrates are in so many different types of foods, that’s obviously an oversimplified message—and it’s not fair to all of the awesome sources of carbohydrates in the world of food. Not all carbohydrate-rich foods are the same. In this unit, you’ll learn to appreciate the nutrient-dense carbohydrate foods, identify which don’t offer as valuable a nutritional package, and understand how a balanced diet can include all of them.


Unit Learning Objectives

After completing this unit, you should be able to:


  1. Classify the different types of carbohydrates, identify their food sources, and discuss how these carbohydrates are digested and absorbed in the body.
  2. Define the guidelines for total carbohydrate, fiber, and added sugar intake.
  3. Explain how glucose is regulated and utilized in the body and describe how the body adapts to a low carbohydrate intake.
  4. List the causes, complications, and treatment for different types of diabetes.
  5. Describe the health benefits, types of, and food sources of dietary fiber.
  6. Differentiate between whole and refined grains in foods by examining food labels.
  7. Distinguish between added and natural-occurring sugars in foods, and discuss health implications of too much added sugar.
  8. Identify sugar substitutes in foods, and describe potential benefits and drawbacks of sugar substitutes.


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Nutrition: Science and Everyday Application, v. 1.0 Copyright © 2020 by Alice Callahan, PhD; Heather Leonard, MEd, RDN; and Tamberly Powell, MS, RDN is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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