Carbohydrates: Fuel for Life

The human body is a miraculous machine composed of trillions upon trillions of cells all functioning together to sustain life. Consider each cell like a mini reactor creating power for itself which in turn powers larger systems – like a single cell in the heart’s right atrium working in concert with other cells to create and operate the heart as a whole.

Each of these mini generators requires fuel to perform their specific tasks, and this is where carbohydrates come into play. While the body is adept at using other macronutrients as fuel, carbohydrates are the easiest to convert into glucose (aka blood sugar) and tend to be the principal energy source for the human body when they are present though at rest fats become the primary source. (When carbohydrates are ingested, the body tends to increase their usage first before using fats for energy.)

As such, to maximize health it is crucial to understand the various forms of carbohydrates and how the body uses them. So, rev up your cellular engines as we take a closer look at carbohydrates’ unique role in the human body.

The first thing to remember about carbohydrates is that when they are finished being metabolized (digested and turned into a usable substance) they become glucose in the blood or glycogen in muscle and fat cells to be stored for later use. How quickly carbohydrates metabolize has important ramifications for health. The faster a carb turns to glucose, coupled with the quantity consumed, the greater the insulin response will be.

Insulin is a hormone that facilitates glucose transport into a cell. Think of it like the hose which transports fuel into your vehicle. When blood glucose levels are higher than is needed by the cells, extra insulin is produced to transport the excess glucose – akin to higher pressure in the hose. Eventually, the cells stop responding to insulin leading to insulin resistance and eventually diabetes. Understanding which carbs lead to a heightened insulin response is paramount to maintaining health.

Carbs come in three main flavors: monosaccharides, disaccharides, and polysaccharides. Monosaccharides are simple carbs and are the quickest to metabolize into glucose; they include fruits, juices, syrups, honey, sweetened drinks, and anything with added sugar. These will elicit a rapid insulin response and are best consumed before physical activity or earlier in the day so that their energy is better used in daily activity.

Monitoring simple carb intake is important so as to not overly inundate the blood with glucose. Ideally, simple carbs would make up a small portion of one’s diet in order to utilize fats for energy at rest. Breaking down more slowly than monosaccharides, disaccharides are the next classification and include lactose, sucrose, and maltose.

Common foods that contain disaccharides are dairy products and breakfast cereals. Finally, polysaccharides are the most complex carbohydrate taking the longest to metabolize and are composed of foods that are high in starch and fiber. Sources of polysaccharides include breads (preferably whole wheat or oat bran), hearty cereals, oats, fibrous veggies, potatoes, rice, nuts, seeds, and legumes among others.

Having discussed the various types of carbohydrates, the following section will review some important considerations when choosing what carb sources to include in one’s diet.

First, the quality of carbohydrates is vitally important. Food high in carbohydrates often contains important micro/phytonutrients. However, refined/processed sources of carbs usually lack these necessary components. For example, if for a snack you had a choice between apple slices and celery sticks versus potato chips and a candy bar, both would offer carbohydrates that your body would turn into glucose, but the first pairing would also include a plethora of essential micronutrients which would add to your overall health and long-term satiation.

Second, usually the more refined a carb source is, the faster it will turn to glucose in the body. For instance, white bread will almost instantly metabolize into energy whereas whole-grain options will take a bit longer. With this knowledge, one can plan out and anticipate their optimal carbohydrate intake.

Finally, it is also useful to have an understanding of what carb sources produce a high glycemic response. One helpful tool for this is the Glycemic Index score (GI score) which is a numerical representation of how fast 50g of carbohydrate turns to glucose and its effect on blood sugar levels in two hours. A score between 0 and 55 is low, 56 to 69 is moderate, and 70 to 100 is large with the larger score equating to greater glucose response. Helpful charts and information for GI scores of specific foods can be found online.

Additionally, the Glycemic Load score (GL score) is useful as well as it takes into account the quantity of carbohydrates consumed. GL is calculated as the quantity of carb in grams multiplied by the GI score divided by 100: Carb(g) x (GI score/100). For this equation a score at or below 10 is low, 11 to 19 is moderate, a 20 or greater is large. Using these scores, one can get an estimation of their body’s glucose response to specific carbohydrate sources. Over time, one will develop a more intuitive sense of what foods will lead to a greater glycemic response as they practice making nutritionally informed decisions.

Following this analysis, the tools are laid out to begin honing one’s carbohydrate selection. Most importantly, while making healthy decisions is important, it should not become a source of stress or anxiety. Striving to be healthy 80% of the time with the other 20% being open to variability is a sound way to stay on track while allowing space for enjoyment and improvement. As you practice mindful carbohydrate consumption, be on the lookout for the next installment in the nutrition series where we will be investigating the role of fats in metabolism.

Written By: Michael Hollinger, CPT

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