Carbohydrates 101: Nutrition Basics for the Athlete


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Lots of athletes talk about diet plans, calorie intake, etc…without really understanding the basics. To this end, I would like to start a series on each of the basic nutrients. First up…carbohydrates. Let’s call it carbohydrates 101.

In today’s post I want to provide athletes of Fuel For Endurance with an overview of carbohydrates, the difference between simple and complex carbs, and how much you need each day.


So What Is the Purpose of Carbohydrate Anyway?

One could argue that carbohydrates are the most controversial topic in nutrition. As the term suggests, carbohydrates contain carbon(s) and water as part of their structure.

The primary goal of carbohydrate is to provide the energy our body needs to do work.  I will say that again because it is important—energy production is really the main purpose of eating carbohydrates. Certain organs like the brain really function well on carbohydrates.


Complex vs. Simple Carbohydrate

Simple carbohydrates are carbs that require minimal or no digestion at all. This means they enter the bloodstream very rapidly. Common examples of simple sugars include regular soft drinks and other convenience foods. These products tend to provide little or no nutritional value just lots of “empty” calories.

Of course there are exceptions to every rule. For instance, fruit is primarily made up of simple sugar. Fruits like apples, bananas, and berries provide lots of health benefits and the peel or skin contains another form of carbohydrate called fiber. We will discuss this shortly.Carbohydrate 101

The simplest carbohydrate is called a monosaccharide. There are 3 key 6 carbon monosaccharides: glucose, fructose, and galactose. The only real difference between these monosaccharides is their structure. Also, you probably know that glucose (shown to the right) is the most common and is generally referred to as “blood sugar.”

Monosaccharides can combine with one another to form disaccharides.

  • fructose + glucose = sucrose or table sugar.
  • glucose + glucose = maltose…my personal fav cause it is found in beer
  • glucose and galactose = lactose or milk sugar.

Both mono and disaccharides are generally termed “simple sugar.”

When many monosaccharides combine (usually hundreds and even thousands) it is called a polysaccharide, starch, or complex carbohydrate. You may also hear folks in the media refer to them as “slow” carbs. Examples include whole grains, whole wheat pasta, and potatoes.

This plant polysaccharide is considered “complex” because it requires more time for digestion. In contrast to simple sugars, digestive enzymes in the small intestine must break down the bonds that hold the monosaccharides together.

As you consume carbohydrates, even the complex variety, they will eventually be digested into their simplest form and that’s either glucose, fructose, or galactose. However, the body will eventually convert fructose and galactose to glucose.

The fate of glucose depends on the energy needs of the body. Glucose can either be used immediately for energy or stored for later use.

The storage form of carbohydrate in our body which is called glycogen. Carbs are stored as glycogen in the muscle and the liver. If you are an athlete that eats a high carb diet maximizing muscle and liver glycogen stores is important for those long workouts and races.


So Where Does Fiber Fit In?

Fiber is the indigestible form of complex carbohydrate. Our body does not have the enzymes to break down fiber so almost all of it passes through our gut and is excreted in feces. Example of foods containing fiber include oatmeal, fruits/vegetables, whole grains, and legumes (beans).

There are two types of fiber: soluble and insoluble.   Soluble fiber dissolves in water, becomes viscous and is fermented by bacteria in the colon. Insoluble fiber does not dissolve in water. The United States Department of Agriculture (USDA) recommends a target of 25-35 g of fiber per day or 14 g per 1000 kilocalories.

Functions of fiber in the body include:

  • AIDS in digestion (Both)
  • REDUCES the risk of heart disease, diabetes, obesity, and certain types of cancer. (Soluble)
  • Helps promote REGULARITY (Insoluble)
  • FEELING full or satiety (Both)


How Much Carbohydrate Do We Need?
The USDA recommends between 45-65% of our diet be carbohydrate. For example, if you were eating a 2,000 calorie diet you would need 900-1300 calories from carbs.

Training load, weight goals, and diet philosophy are several factors that determine how much carbohydrate you should consume on a daily basis.


So that’s it for carb basics!  We talked all about the differences between simple and complex carbohydrates, how carbohydrates are stored in our body, how much we need, and why fiber should be an important part of your diet. Next we will ask the question, “Does a high carbohydrate diet improve performance.”

P.S. I hope you learned something from this article. If you did please share it with some who might also find it valuable. Please comment below and I’d love to ask any questions you might have about carbohydrates.

Until next time…train hard and eat well.

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