Did anyone else feel bad for Regina George when she was duped by Cady Herron when she asked if butter was a carb? I found myself laughing at the time the movie came out, but after a year of working with clients and more time talking with others, it’s clear that it can be hard for people to think about food in terms of their macro nutrients, especially carbohydrates.
So what is a carbohydrate and why is it important?
This post will talk about the what because it’s slightly more complicated that you think. There’s a little bit of the why in here, but that will mostly come in the next post.
Ok, so what are carbohydrates?
Carbohydrates are the first source of energy for us. They are fuel for us when we are sitting, sleeping, exercising or thinking of doing all of those things.
The Acceptable Macronutrient Distribution Range (AMDR) suggests that carbohydrates make up 45 to 65% of your diet…if you’re consuming 2,000 calories a day. We’ll talk about this more in the next post because I think it’s safe to say that most people won’t fit these guidelines.
The Institute of Medicine set the Recommended Dietary Allowance (RDA) for carbohydrate intake to a minimum of 130g a day. Obviously, this amount wouldn’t fit the AMDR – it would be too little based off a 2,000 calorie diet. The RDA number is set based off the estimated minimum use of glucose for the brain for an average body, which means it’s relative (Institute of Medicine, 2005). It might be slightly lower or slightly higher.
Since we have some of those basics out of the way, let’s start small, molecular small.
This is where biology and chemistry meet.
Carbohydrate means hydrated carbon (Reece, Taylor, Simon, Dickey, & Hogan, 2015). At the molecular level (and trust me this is helpful to know later) carbohydrates are made up of CH2O – 1 carbon, 2 hydrogen and 1 oxygen. In biology we actually learned a little upbeat rhyme of the abbreviates to memorize the molecular make up for carbohydrates, lipids (fats), nucleic acid and protein: CHO CHO CHOPN CHON, but you had to study so you knew how many of each were needed. Moving on…
The simplest carbohydrate is a monosaccharide – you’ll find these in glucose and fructose, which are sugars that carbohydrates break down to (Reece, Taylor, Simon, Dickey, & Hogan, 2015). You’ll find fructose in fruit. Glucose can be found in corn syrup and plants and found in the blood stream after certain carbohydrates are consumed and broken down. No your blood isn’t made of corn syrup.
Below are the chemical layout for glucose and fructose at the molecular level so you can see the difference.
When you add two monosaccharides together, they form a disaccharide. For this binding to happen, water has to be lost. This is how we get maltose, which is used to make beer, malt whiskey and malted milk candy (Thompson & Manore, 2015).
Below is a picture of maltose, so you can see how glucose joins together. It’s like they’re holding hands if molecules had hands.
We also get sucrose when glucose and fructose join together. Sucrose is found in plants and it’s how we get table sugar (Thompson & Manore, 2015).
Below is a picture of sucrose. See more water is lost. Goodbye H2O!
A longer chain, known as a polysaccharide are made up of hundreds of thousands of monosaccharides connected by water loss. Starch is an example, this is found in plants and contains glucose mononers. Glucose is stored in us in the form of glycogen in our muscles as a form of energy.
There’s a lot of ‘oses.
Here’s a few other ‘oses:
- galactose – doesn’t occur alone in foods. It combines with glucose to create lactose.
- lactose – “milk sugar”. A common disaccharide found in cow’s milk and breast milk.
- ribose – five-carbon monosaccharide produced in our bodies from eating other carbohydrates. Can be found in the genetic material in our cells
Knowing the information above can be helpful for this next part. Carbohydrates are considered either simple or complex (Thompson & Manore, 2015). Like stated above the simplest carbohydrate is a monosaccharide and consists of one sugar; disaccharides are also simple and consist of two molecules of sugar. As you imagine, the most complex is the polysaccharide that is made up of hundreds of thousands of monosaccharides.
What is considered simple?
- fruit (fructose)
- vegetables (fructose)
- milk (lactose)
- fermented beverages (maltose)
- sweeteners like honey, maple syrup, table sugar, brown sugar (sucrose)
What is considered complex?
- starches including grains like rice, wheat, corn, oats and barley
- legumes like peas, beans and lentils
- tubers like sweet potatoes and yam
The digestion process is different for each macronutrient (fat, carbohydrates and protein), which means they breakdown at different rates (National Institute of Diabetes and Digestive and Kidney Diseases, 2017). Carbohydrates breakdown the fastest out of the macronutrients with fat being the slowest.
There are a few enzymes that help breakdown carbohydrates.
- Salivary Amylase is found in the mouth in your saliva
- Pancreatic Amylase and Maltase are found in the pancreatic juices (yes, gross I know) that are released into the small intestine to breakdown maltose
- Sucrase and Lactase are found in the small intestine and help breakdown sucrose and lactose, respectively
*side note: when your body lacks the ability to create enough enzymes you may find intolerances like lactose in tolerant – you lack enough lactase enzyme to breakdown lactose. This can result in bloating or other digestive issues.
This is important to know the rate of digestion for a couple reasons:
1. Simple carbohydrates are digested and absorbed more easily causing a quicker energy utilization, which is why you may feel a “spike” in energy after eating something high in sugar, but then feel a “crash” later. This is also why individuals who are diabetic are encouraged to eat low-glycemic foods – foods that will breakdown at slower rates causing less of an increase in blood glucose since their bodies can’t produce insulin at all or don’t produce enough.
2. Our bodies can’t utilize complex carbohydrates in their consumed state, they need to be broken down to glucose (Thompson & Manore, 2015). These foods also contain fiber, which impacts how satiety controlling hormones are released (Chambers, McCrickerd, & Yeomans, 2015). This is why these foods keep us fuller longer even though protein has the highest satiety effect out of all three macronutrients.
When there’s not enough carbohydrates for this process the body turns to fat. To learn more about that, please check out this post.
Understanding the difference between simple and complex carbohydrates can be helpful for a couple of reasons.
1. You can create a meal plan that combines complex carbohydrates with other foods to not only provide energy in the immediate time, but help you stay feeling full longer. That’s why oats and peanut butter “stick” with you for a long time. Being satisfied for a longer period of time prevents snacking and can assist you in staying in caloric deficit if you are seeking fat loss.
2. You can create a meal plan that prevents or lessens “energy crashes”. Like stated above, complex carbohydrates take a longer time to breakdown a, which means glucose enters the blood slower so feeling tired or fatigued are less likely or are less impactful.
Carbohydrates that aren’t easily digested and broken down into this simple state are classified as fiber.
What is fiber?
Fiber is also a carbohydrate and is considered a polysaccharide, but it’s not easily digestible so it doesn’t provide energy to us (Thompson & Manore, 2015). There are two kinds of fiber:
- dietary – nondigestible parts of plants that make the form of the plant like leaves
- functional – nondigestible parts of plants that are extracted or manufactured in a lab that is added to foods for health benefits
Even though fiber doesn’t provide energy to us, fiber is important because it helps regulate blood sugar. It also helps prevent constipation when consumed in a moderate (relative to an individual) amount, however, it can also cause constipation when over consumption occurs (also relative to an individual) (Anderson, et al., 2009). Foods with fiber also help regulate satiety hormone leptin, which tells our brains that we’re no longer hungry.
Currently, the recommended amount of fiber daily is 14g per 1,000 calories consumed, however, this number is relative to an individual and may be a little more or less based on your own caloric intake, weight and activity level. You should listen to your body to determine true needs. I personally need a little less fiber or I get bloated and constipated #everyonepoops.
Ok, so we know carbohydrates are the first source of energy for us. We know they breakdown at different rates. We know they’re relative to each individual. We know that they are found in fruits and veggies just like they are found in cookies and pizza.
Before we get into why they’re important and what the do for us, think about the carbohydrate sources you consume on a regular basis. Do they make you feel energized? Do you crash quickly in the day? Do you feel bloated? Do you combine simple and complex in your diet? Do you get enough fiber?
Anderson, J. W., Baird, P., Davis, R. H., Ferreri, S., Knudtson, M., Koraym, A., . . . Williams, C. L. (2009). Health Benefits of dietary Fiber. Nutrition Reviews, 188-205.
Chambers, L., McCrickerd, K., & Yeomans, M. R. (2015). Optimising Foods for Satiety. Trends in Food Science and Technology, 149-160.
Institute of Medicine. (2005). Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids. Washington, D.C.: The National Academies Press.
National Institute of Diabetes and Digestive and Kidney Diseases. (2017, December). Your Digestie Syste & How it Works. Retrieved from National Institute of Diabetes and Digestive and Kidney Diseases: https://www.niddk.nih.gov/health-information/digestive-diseases/digestive-system-how-it-works
Reece, J. B., Taylor, M. R., Simon, E. J., Dickey, J. L., & Hogan, K. (2015). Campbell Biology: Concepts and Connections. New York: Pearson Education.
Thompson, J., & Manore, M. (2015). Nutrition: An Applied Approach. San Francisco: Pearson Education.