Carbohydrates: Simple vs. Complex & the Glycemic Index

Carbohydrates are an essential part of human nutrition. They are found in the majority of foods we eat, including fruits, vegetables, grains, and dairy. Knowing what carbohydrates are allows us to use them effectively to enhance our health and athletic performance. 

The word carbohydrate comes from its chemical structure. Carbohydrates contain carbon, hydrogen, and oxygen, with the hydrogen/oxygen ratio reflecting that of water. You can see why the name is carbo-hydrate (CH2O).

There are two types of digestible carbohydrates, sugars and starches. Sugars are also called saccharides. Depending on how many saccharides are found within the molecular structure, that will determine whether it is a simple or complex carbohydrate. 

Simple Carbohydrates

Monosaccharides (one), and disaccharides (two), are both classified as simple carbohydrates. 

The types of monosaccharides are:

  • Glucose: Found circulating in the blood and is supplied through carbohydrate digestion. Can also be found in some foods such as corn syrup and endurance gels.
  • Fructose: Very sweet and is found in fruit, honey, and high fructose corn syrup. 
  • Galactose: You won’t find this in food, but rather it is released after the digestion of lactose. 

The types of disaccharides are:

  • Sucrose: This is common table sugar, can also be found in molasses and some fruits and veggies.
  • Lactose: This is the sugar found in milk.
  • Maltose: Is formed as a result of starch digestion.

Examples of simple carbohydrates include white bread, crackers, baked treats, sweet drinks, juices, and candy. If the food is very sweet, does not contain a lot of fiber, and is processed, there is a good chance it is a simple carbohydrate.

Complex Carbohydrates

Complex carbohydrates are called polysaccharides because they are made up of many saccharides, or many single glucose units. The types of polysaccharides are:

  • Starches: Contain coiled and branching chains of glucose units. Cooking and breaking down the starches helps make digestion easier.
  • Resistant starch: These starches are resistant to digestion and enter the colon almost completely intact. Resistant starch is important for gut health and can protect against colon cancer. Think fiber.
  • Glycogen: Glycogen is the stored form of carbohydrates that is found in the liver and muscle tissue. The body stores glycogen and uses it when needed, such as fasting periods or during intense activity and exercise. Glycogen is obtained from dietary carbohydrates. 
  • Oligosaccharides: These are partially broken down starches that contain 3-10 glucose units. You can find these in baby formula and sports drinks.

Examples of complex carbohydrates are oatmeal, brown rice, whole wheat bread, sweet potatoes, and beans.

In short, simple carbs digest and absorb faster due to their simple structure, thus providing the body with glucose (energy) at a faster rate. However, faster does not mean better. We must consider the glycemic index of carbohydrates as well. Foods high on the glycemic index will cause blood sugar spikes and be available as energy almost immediately after consumption. This can be beneficial if you are going to train soon or will be needing that energy right away. Complex carbohydrates are lower on the glycemic index and will take longer to digest, meaning the energy will not be available until after digestion has fully occurred. 

Some long distance runners choose to intake carbohydrates as they go. Products like endurance gels and drinks contain glucose and fructose as their main ingredients because they provide almost immediate energy. Complex carbohydrates have to be eaten and digested before commencing exercise. Our overnight oatmeal is a complex carbohydrate, meaning you should consume it well before you train in order to allow it time to digest properly. The energy you get from the oatmeal will be a slow burn rather than a quickly passing boost. 

The Glycemic Index

The glycemic index (GI) is a measurement that shows the effect of carbohydrates on blood glucose levels. A high GI value means the food will raise blood glucose level to a greater extent compared to low GI value. Once glucose is in the bloodstream, the pancreas secretes insulin that moves glucose into body tissue and out of the blood. It is important to maintain a healthy awareness of the GI of foods because uncontrolled intake can lead to an overworked pancreas and over the long term, diabetes.

There are various factors that can change the GI of food. Including:

  • Type of carbohydrate
  • Particle size and processing of the carbohydrate
  • Cooking or preparation
  • Presence of fiber (lowers GI)
  • Presence of fat (lowers GI)
  • Presence of protein (lowers GI)
    The type of carbohydrate will be a big factor because whether it is a simple or complex carb will reflect in the GI. The particle size of the carbohydrate will also affect GI because a more finely produced and processed carbohydrate will be more broken down and have a greater surface area that will come in contact with digestive enzymes. Think about instant oatmeal vs.  rolled oats. The instant oatmeal will be made of fine flakes, where the rolled oats will be a more complete grain that takes longer to digest. Depending on how you cook a carbohydrate will alter its GI. If you cook it down, the molecules will break down, speeding up the digestion process and raising its GI value. Overnight oatmeal is broken down with a soak, meaning the grain will be more resistant compared to one that has been cooked in high heat, lowering its GI value.
    The presence of fiber will thicken the food mass, slowing the digestive process. Fat slows gastric emptying and also interferes with the action of digestive enzymes. The presence of protein stimulates the secretion of insulin, making the removal of glucose from blood more effective. 
    As we developed our oatmeal, we took all of these factors into consideration. We use a whole grain, gluten free, organic rolled oat. The complex carbs in rolled oats inherently contain fat, protein, and fiber. We include a 3 seed blend of flax seeds, chia seeds, and hemp seeds, adding healthy fats, fiber, and protein. This makes our oatmeal low on the GI scale and a complete and nutritious meal. It does take time to digest, so you don’t want to eat it right before training. Eating oatmeal as a breakfast or a couple hours prior to training will provide you with a steady and effective source of energy.

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