Article Series

  1. Carbohydrates - Energy Supply For The Body
  2. Complex Carbohydrates For Sustained Energy
  3. How Many Carbohydrates Per Day?
  4. Carbohydrate Foods

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Carbohydrates - Energy Supply For The Body

Carbohydrates - Energy Supply For The Body
Table Of Contents
  1. Classification of Carbohydrates
  2. Glucose from Carbohydrates
  3. Proteins Slow Down Carbohydrate Absorption
  4. From too much glucose comes body fat
  5. Good energy supply through filled glycogen stores
  6. Carbohydrate deficiency and empty glycogen stores lead to muscle breakdown
  7. Carbohydrates for Muscle Building
  8. Glycogen Binds Water
  9. Choose Complex Carbohydrates

Carbohydrates are among the macronutrients and are the body's number one source of energy. The energy content of carbohydrates is 4.1 kcal per gram 1. Carbohydrates are made up of carbon, hydrogen, and oxygen. Depending on their structure or composition, they can be absorbed by the body faster or slower. They are particularly important for training and regeneration, along with proteins.

The group of carbohydrates also includes fiber, which is indigestible to humans but still very important for a healthy intestinal flora and protection against cancer 2.

A plant-based diet rich in fruits and grains is particularly high in carbohydrates (see the high carb foods) and fiber (see the fiber-rich foods).

Classification of Carbohydrates

Carbohydrates are classified into two groups based on their structure:

Glucose from Carbohydrates

In the digestive tract, carbohydrates (excluding fiber) are broken down into glucose by digestive enzymes and released into the bloodstream (blood sugar). This leads to an increase in glucose levels. At the same time, the pancreas is stimulated to release insulin, which raises insulin levels. The released insulin transports glucose to cells (including the brain, muscle cells, and liver) 3. Metabolic reactions then occur in the cells, ultimately producing energy (ATP) from glucose and oxygen. The impact of foods on blood sugar levels can be determined using the calculation of the glycemic load based on the glycemic index.

Proteins Slow Down Carbohydrate Absorption

Oftentimes, carbohydrate-rich foods are consumed with a very low percentage of fats and proteins. This leads to sugar molecules entering the blood more quickly because digestion does not need to "deal" with fats and proteins. Therefore, it is advisable to always eat carbohydrates with proteins, as they slow down the absorption of carbohydrates from the food 4.

From too much glucose comes body fat

Carbohydrates are stored in the form of glycogen (which is the storage form of glucose), also known as animal starch or liver starch, in the liver and muscles. A healthy adult can store about 500 g of carbohydrates 5. Of this, about 90 to 110 g is stored in liver glycogen, about 400 g in muscle cell glycogen, and 25 g as glucose in the blood. If the glycogen stores are full and there is still glucose in the blood, the excess glucose is sent back to the liver. There, it is converted into fat and stored as fatty tissue in the body and liver. This fat layer then serves as a reserve for times of low food intake or during very intense exercise.

According to study results, it should be noted that a carbohydrate-rich diet compared to a protein-rich or one with many unsaturated fatty acids carries a higher risk of coronary heart disease 6.

Good energy supply through filled glycogen stores

To be able to provide the body with energy in the short to medium term, for example during physical exertion, the glycogen stores should always be filled. Full glycogen stores are particularly important during intense or endurance training. The stores are depleted when no or too few carbohydrates (in the form of glucose) are supplied. To ensure that the body can be fully exerted in terms of energy, the glycogen stores should always be full.

Carbohydrate deficiency and empty glycogen stores lead to muscle breakdown

If the body is not supplied with enough carbohydrates, there can be a decrease in performance and concentration during training (see carbohydrate needs). If the glycogen stores are not sufficient, the stored fat is used for energy. Since the brain uses glucose as an energy source, a deficiency can lead to fatigue, concentration weaknesses and dizziness 7. In addition, a glucose deficiency leads to reduced physical performance.

Study results show that muscle breakdown occurs when the glycogen stores are depleted during training. 8. This is because when carbohydrate intake is too low, the glycogen stores are quickly depleted. The body then searches for available energy, which it also finds in amino acids or proteins, which come from the diet or tissue such as muscle cells. They are converted into glucose (gluconeogenesis). One consequence is muscle breakdown.

Carbohydrates for Muscle Building

The body requires additional energy, especially during intense physical activity. Depending on the planned training intensity, the body should be provided with the necessary energy before the activity (and also during longer activities). The focus should always be on consuming complex carbohydrates.

When muscle growth occurs (muscle mass is built), the body also requires more energy so that enough energy is available for the "new" muscles and muscle-reducing processes are avoided.

Glycogen Binds Water

Carbohydrates in the form of glycogen bind water in the body 9. Up to three grams of water can be bound to one gram of stored glycogen. Therefore, eating a lot of carbohydrates can cause a bloated appearance. Additionally, having too much sugar in the body can cause rapid weight fluctuations.

Choose Complex Carbohydrates

Choosing the right carbohydrates has a significant impact on health since carbohydrates are related to diabetes, high blood pressure, and obesity. Therefore, when selecting carbohydrates, one should primarily opt for vegetables. They contain many complex carbohydrates that are slowly processed by the body and transferred to it, in addition to minerals and fiber. Furthermore, whole-grain products are highly recommended due to their nutrient density. Processed foods such as white bread or polished rice contain many simple carbohydrates that should be avoided.