Carbohydrates: The Basics

Carbohydrates are defined as compounds made of one or many sugars. We all love them for their taste but we need them because they are best source of energy for the body to fuel muscles and they promote good health. In this post, I’ll address the basics about carbohydrates and debunk some myths about their value to our diets.

There are two forms of sugars that compose simple carbohydrates, they are monosaccharides and disaccharides. Monosaccharides are single sugar units. There are three types of monosaccharides called glucose, fructose, and galactose. Disaccharides are two sugars linked together. There are three types of disaccharides called:

• maltose (glucose + glucose)
• sucrose (fructose + glucose)
• lactose (galactose + glucose)

Simple carbohydrates are absorbed by the body fairly easily because they do not require much work (or any work in the case of monosaccharides) to be broken down into small enough pieces to be drawn into the bloodstream.

Complex carbohydrates (like fiber, glycogen, and starch) are also known as polysaccharides. A polysaccharide is a very long chain of sugars; because the link is so long, it must be broken down into smaller components (monosaccharides) before the body can absorb them. This means that complex carbohydrates are absorbed slower than simple carbohydrates. Glycogen is the human body’s way of storing glucose (a.k.a blood sugar) for later use. Glycogen is converted to glucose when the body is running low on blood sugar and glucose is converted into glycogen when blood sugar levels are high. Starch is very similar to glycogen, except it is a plant’s way of storing glucose. Fiber is a polysaccharide that cannot be broken down by the human body. Although we cannot absorb it that doesn’t mean it is useless, fiber has numerous benefits for the body.

Fiber:

• decreases the risk of heart disease
• regulates blood glucose
• promotes healthy gastrointestinal function
• encourages a healthy body weight

There are plenty of myths circulating about carbohydrates, most saying that they should be avoided for anyone trying to lose or maintain a healthy weight. However, this is not the case. Carbohydrates should account for anywhere between 45 and 65% of macronutrients consumed in the diet. This means that carbohydrates are not to be avoided! Authors Ellie Whitney and Sharon Rolfes state that “epidemiological studies find an inverse relationship between carbohydrate intake and body weight. Those with the highest carbohydrate intake have the lowest body weight and vice versa.” Now, keep in mind that they are referring to the wholesome kind of carbs, whole-grain and unrefined. On the flip side, too much sugar (i.e. monosaccharides) added into the food is associated with the presence of more body fat. “Sugar” in this case is referring to refined carbs. Also, foods high in refined sugars are lacking in protein, vitamins, minerals, and fiber which whole-grain carbohydrates have. Thankfully, we can easily omit these unfulfilling types of carbohydrates from our diets. For example, a sweet ice tea can be replaced with a glass of unsweetened tea or water.  Another example is replacing a sugary cereal like Cinnamon Toast Crunch with Cheerios.

In conclusion, there are two key points to take away from this post. The first is that carbs are not always your enemy. The occasional additional sugar can sweeten your day without ruining your diet. The second is that carbs are not always beneficial for you. Too much added sugar will do more harm than good.

--Hannah

Clark, N. (2014). Carbohydrate: Simplifying a Complex Topic. In Nancy Clarks' Sports Nutrition Guidebook (5th ed., pp. 111 - 135). Newton, MA: Sports Nutrition Services.

References

Sizer, F., & Whitney, E. (2012). Carbohydrates: Sugar, Starch, Glycogen, and Fiber. In Nutrition: Concepts and Controversies (12th ed., pp. 109, 111, GL-4). Belmont, California: Yolanda Cossio.

Whitney, E., & Rolfes, S. (2013). The Carbohydrates: Sugars, Starches, and Fibers. In Understanding Nutrition (13th ed., p. 99, 118,125). Belmont, California: Yolanda Cossio.

Taubes, G. (2008). Diabetes and the Carbohydrate Hypothesis. In Good calories, bad calories: Fats, carbs, and the controversial science of diet and health (p. 112). New York, New York: Anchor Books.

Clark, N. (2014). Carbohydrate: Simplifying a Complex Topic. In Nancy Clarks' Sports Nutrition Guidebook (5th ed., pp. 111 - 135). Newton, MA: Sports Nutrition Services.