Functions and types of carbohydrates

Carbohydrates have many important functions in the human body, the most important of which is to provide energy to the cells. Glucose is the superior energy material for humans. If the meal is rich in carbohydrates (especially the simple ones) as well as in protein and fat, then first of all carbohydrates will be used to produce energy. If they run out, the body will use fats and proteins sequentially. If you do not provide adequate supply of carbohydrates after training, the body will use muscle protein to produce energy and your workout can bring unwanted results.

Carbohydrates are a very large and diverse group of compounds. It includes simple molecules (glucose, fructose, sucrose) and very complex compounds such as starch or fiber. We can often hear about “bad” and “good” carbohydrates or “bad” and “good” sugars. Is it really like this? The energy demand and the type and intensity of training determine what type of carbohydrates is right for us.

Simple carbohydrates, called sugars, will give you a shot of energy in a short time. We should reach for sugars during a long, intense physical effort that quickly consumes energy reserves. Daily physical activity related to work and home, a faster walk or short jogging do not consume glucose supplies (stored in the form of glycogen) to such an extent. Complex carbohydrates are better in everyday situations and with moderate physical activity. Their characteristic features are a slow decomposition into simpler compounds and a steady supply of energy. Why is it so important? If there are no large “leaps” and “drops” of glucose in our blood, we will feel full longer and our desire to have snacks will be smaller.


Sources of simple and complex carbohydrates

The most important and most popular complex carbohydrate is starch. Starch consists of many glucose molecules released during digestion processes. Products rich in complex carbohydrates are primarily flour, bread, pasta, cereals, rice, potatoes, oatmeal and legumes. The more the product is “processed”, the more carbohydrates it contains. It is therefore worth choosing whole grain products from coarse milling and less purified (eg rich in husk).

Carbohydrates may also be affected by heat treatment. The more simple carbohydrates, the larger the glycemic index (GI). What does it mean? Glycemic index determines the average increase of glucose after consuming 50 g of product, compared to 50 g of pure glucose. High GI products are rapidly digested and absorbed, resulting in a rapid increase followed by a rapid drop in blood glucose. Our daily diet should be rich in products with a low GI, and only in certain situations (increased energy demand) we should eat meals rich in simple sugars – that is, those with a high GI. Natural and most recommended sources of simple sugars are fruits, natural juice or honey.


Some important information that will help you balance the daily dose of carbohydrates:

  1. 1 g of carbohydrates (the simple and the complex ones) equals about 4 kcal.
  2. Energy from carbohydrates should amount to 45-65% of the daily requirement.
  3. Energy from simple sugars (glucose, fructose, sucrose) should not exceed 10% of daily demand.
  4. Choose products with a low glycemic index (IG).
  5. The amount of carbohydrates necessary to satisfy basic metabolic needs (especially those related to normal brain function) is about 130 g / d.



1: Korsmo-Haugen HK, Brurberg KG, Mann J, Aas AM. Carbohydrate quantity in the dietary management of type 2 diabetes – a systematic review and meta-analysis.

Diabetes Obes Metab. 2018 Aug 11. doi: 10.1111/dom.13499.

2: Sainsbury E, Kizirian NV, Partridge SR, Gill T, Colagiuri S, Gibson AA. Effect of dietary carbohydrate restriction on glycemic control in adults with diabetes: A systematic review and meta-analysis. Diabetes Res Clin Pract. 2018 May;139:239-252. doi: 10.1016/j.diabres.2018.02.026.

3: Sartorius K, Sartorius B, Madiba TE, Stefan C. Does high-carbohydrate intake lead to increased risk of obesity? A systematic review and meta-analysis. BMJ Open. 2018 Feb 8;8(2):e018449. doi: 10.1136/bmjopen-2017-018449.

4: Hall KD. A review of the carbohydrate-insulin model of obesity. Eur J Clin Nutr. 2018 Jan;72(1):183. doi: 10.1038/ejcn.2017.156.


Anna Lewandowska

Athlete and nutrition specialist. Multiple medalist of the national in traditional karate in European, and World Championships. Author of workout plans and books about healthy lifestyle that everyday helps her motivate over a million of people to change to a healthier lifestyle.

Founder of Healthy Plan by Ann, Diet & Training by Ann. CEO of Foods by Ann. Co-founder of Baby by Ann.

Wife of footballer Robert Lewandowski, captain of Poland's national football team and Bayern Munich player. Read more »

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