This famous phrase heard too often.

Before expressing an opinion on carbohydrates it is important to really understand their functions.

Carbohydrates, also called sugars or carbohydrates, play an essential role in the functioning of our body. They are a primary source of energy and perform other key functions in maintaining our health and well-being.

First of all, carbohydrates are the main source of energy for our body. When we eat foods high in carbohydrates, such as grains, vegetables, fruits and grain products, they are digested and converted into glucose, a form of sugar that our body can use for fuel. Glucose is then transported to our cells, where it is metabolized to produce ATP (adenosine triphosphate), the main energy molecule used by our body.

In addition to providing energy, carbohydrates play a crucial role in brain function. Glucose is the primary fuel source for the brain, and it is necessary to support its cognitive and mental functions. The brain uses about 20% of the body's total energy, and it relies primarily on glucose to function optimally.

Carbohydrates also have a role in regulating metabolism. Insulin, a hormone secreted by the pancreas, helps regulate blood sugar (blood glucose level) by promoting the absorption of glucose by cells and encouraging its storage in the form of glycogen in the liver and muscles. Glycogen can then be broken down when energy stores are needed, keeping blood sugar levels balanced.

Additionally, certain types of carbohydrates, such as dietary fiber, play an important role in digestive health. Dietary fibers are complex carbohydrates that our bodies cannot fully digest. They add bulk to stools, promote regular intestinal transit and help prevent digestive problems such as constipation. Dietary fiber may also help control blood sugar levels by slowing glucose absorption and promoting satiety.

In more detail, there are two types of carbohydrates: simple carbohydrates and complex carbohydrates. Simple carbohydrates include glucose, fructose and galactose, which can combine to form more complex carbohydrates such as sucrose (table sugar), lactose or maltose. Complex carbohydrates, on the other hand, include starch, glycogen and dietary fiber.

Carbohydrates perform different functions in our body:

• Providing energy to cells
• Build up glycogen reserves (glucose storage)
• Improve sports performance when consumed around training

The main role of carbohydrates is to provide energy to the cells of our body. Each gram of carbohydrate provides approximately 4 calories. When we consume foods rich in carbohydrates, they are transformed more or less quickly into glucose, which is the preferred fuel for certain cells, particularly brain cells. Indeed, glucose is the exclusive fuel of the brain, which needs around 140 grams of glucose per day to function properly.

Simple Carbohydrates impact blood sugar levels by causing them to rise quickly, meaning they have a high glycemic index. This can lead to easier storage of unused carbohydrates in fatty tissues if physical activity is not performed.

Complex carbohydrates, on the other hand, are made up of several simple carbohydrate molecules. They are more difficult for the body to absorb and are therefore less easily stored in fatty tissues.

Many factors influence the speed of absorption of carbohydrates and therefore the glycemic index of foods. For example, the presence of proteins, lipids or fibers in a food slows down the rate of absorption of the sugar it contains. Additionally, preparation and cooking methods can also influence the glycemic index of a food.

Dietary Fiber is different from other types of carbohydrates because it is not primarily a source of energy. An optimal consumption of around 30 grams of fiber per day promotes good intestinal functioning. Certain fibers, such as those found in fruits, can also help reduce cholesterol levels.

Dietary fiber can slow down the digestion process, which spreads out the absorption of nutrients over time and leads to a feeling of fullness. The slower digestion of dietary fiber also reduces insulin secretion, which promotes better blood glucose utilization and therefore may contribute to reduced fat storage.

References :

• Anderson JW, Baird P, Davis RH Jr, Ferreri S, Knudtson M, Koraym A, Waters V, Williams CL. Health benefits of dietary fiber. Nutr Rev. 2009 Apr;67(4):188-205. doi: 10.1111/j.1753-4887.2009.00189.x. PMID: 19335713. (Benefits of dietary fiber)