There is no such thing like a diet that fits us all and that is 100% right. It always depends very much on who you give a dietary recommendation to. When it comes to sugar, for example…. This topic is somewhat omnipresent. We hear all the time how excessive sugar consumption is bad for our health. In fact, there is a lot of sugar in products we buy at grocery stores. Whether in sweets, sauces, soda-pops, baked goods, sausages, fruit yoghurts or spreads - sugar is one of the ingredients of many products. Sweetened drinks as thirst quenchers significantly increase the sugar consumption of many people, which often leads to an excess of calories and can trigger health issues in the body (Malik & Hu, 2022). Over the last few years, this excessive consumption of especially added sugar has contributed to an increase in body weight of the world population and a rise in the incidence of chronic diseases. We move less (often inadequate level of physical activity!) and we consume too much sugar - this has a detrimental effect on our health.
This is not the only reason why the goal is to reduce sugar in the diet. According to EFSA the intake should not exceed 10% of the total daily energy intake. This applies in particular to added sugar, refined sugar, which has a very low nutritional value and also promotes inflammation. However, some sugar is also found naturally in many foods. This includes fruit, vegetables, milk and dairy products. Of note, sugar in such foods is found in combination with other nutrients that are healthy and important. Calcium, vitamin C, potassium, vitamin A and more are present in these foods.
Should athletes avoid sugar?
Sugar plays an important role in sport. It serves as an important source of energy for our brain and muscles, especially during moderate to high-intensity exercise. The intake of fast, simple carbohydrates serves to delay and minimize fatigue and to maintain performance. Performance will decline very quickly of anyone who fails to ingest recommended amount of carbohydrates during exercise. Simple sugars in particular make it easy for the body to get energy quickly and supply the muscles with the necessary fuel.
Sugar is a form of carbohydrate that is important for athletic performance in a specific context.
While we should therefore reduce refined sugar in our daily diet as much as possible, there are times for athletes where sugar is necessary and beneficial. That's in the context of exercise. Shortly before, during and after exercise, it serves as an energy source. Anyone who fails to ingest enough carbohydrates risks performance decrements and health problems (e.g. relative energy deficiency in sports, increased injury risk). Outside of training or competition, however, the focus is on quality, i.e. nutrient-rich foods with as little added sugar as possible and, for example, higher fiber content. However, it should also be mentioned that carbohydrates - whether complete, fiber-rich or refined - are ultimately broken down into simple sugar molecules (glucose). This is how they are absorbed and stored by our body (glycogen). Whether it's whole grain bread, lentils or a sports drink.
While fast energy is often an advantage during training, meals should be used to provide the body with as many nutrients as possible. Put quality on the plate and with the snacks, on the other hand the simple sugar for energy supply into training (Burke et al., 2011; Brown et al., 2025). This means that gummy drops and fruit gummies can also be used as a carbohydrate source during training. Wonderful in this context, absolutely not necessary and recommended at home on the couch when watching TV. Correct, it depends on the context!
Many recommendations apply under specific conditions
Gluten is another example that is often put into the wrong light. While people diagnosed with celiac disease (gluten intolerance) must avoid products that contain gluten, there is no reason for people without coeliac disease to do so. Gluten is not unhealthy nor does it trigger dangerous inflammatory processes in the body (Wieser et al., 2020, Cortijo-Alfonso et al.; 2024). In fact, gluten-containing foods contain many other important nutrients that are also missing when they are eliminated from the diet. Especially when it comes to fiber, many do not get the recommended daily amount anyway. Anyone who does not suffer from coeliac disease can eat these grain products without any concern.
Shelves are full of protein supplements, you can find protein enriched products in pretty much every aisle or bakery, and you get the impression that we are struggling to meet daily protein recommendations. But most athletes can cover their increased protein requirements with their habitual diet - provided they adjust their energy intake to the training. On the other hand, hunger decreases with increasing age, while at the same time we observe reduced sensitivity of skeletal muscle tissue to dietary protein in older people (anabolic resistance). An increased intake can compensate for this resistance. Due to a lack of hunger, protein shakes and drinking food are good approaches for an adequate intake for this population. So yes, sometimes protein supplements are useful and necessary. Context!
For many, fruit juices are important sources of nutrients. A small glass of multivitamin juice provides plenty of vitamin C and thus contributes to the daily supply of nutrients. Such options are especially helpful for people who struggle to consume the recommended servings of fruits and vegetables. In sports, with modern sports drinks, athletes consume not only glucose but also fructose. As a result, more carbohydrates can be absorbed. In connection with exercise, fructose therefore supplies the muscle with important energy.
Contrarily, anyone who consumes several glasses of fruit juice a day to meet their fluid requirements will absorb a lot of calories and a lot of fructose. In the long term, this can have adverse consequences (e.g. weight gain, metabolic diseases) (Giussani et al., 2022).
In the Western world, the window of energy intake has increased quite significantly. The first energy intake is early morning and we tend to eat until late in the evening. consuming calories over more than 12-13 hours isn't ideal for our health. We see the detrimental consequences in particular in people who do not exercise enough and spread their energy intake over 12 or more hours. For the general population, it is recommended to avoid late eating and limit energy intake to 10 hours.
Interestingly, athletes are also told to avoid eating late because it is not healthy. A hint: context is important! If you are still training in the afternoon or until late in the evening, the late evening is very important recovery time. In this case, you should still consume energy in the evening to support the recovery processes in the body. While we sleep, our body recovers and needs certain substrates to do so. If we go to bed after exercise without additional energy intake, this has a negative effect on performance and health. Exercise impacts our nutrient needs and has consequences for our meal pattern.
Context makes the difference
As the examples given above show, nutrition depends in many cases on who you give recommendations to. Not mentions (due to its complexity) is the field of dietary supplements and ergogenic aids. Again: be careful! More isn't always better, recommendations usually correspond to very specific (clinical!) populations and conditions. The question "if needed at all?" is one to be asked before taking a supplement.
Recommendations for different populations are often thrown into one big pot and applied to everyone. What is unhealthy, unnecessary, or dangerous for some can be healthy, important and useful for others. Context makes the difference in nutrition.
Further reading:
Brown et al. (2025) Sports Nutrition: A Handbook for Professionals. 7th Ed., Academy of Nutrition & Dietetics.
Burke et al. (2011) Carbohydrates for training and competition. doi.org/10.1080/02640414.2011.585473
Cortijo-Alfonso et al. (2024). Effect of Barley and Oat Consumption on Immune System, Inflammation and Gut Microbiota: A Systematic Review of Randomized Controlled Trials. Curr Nutr Rep13, 582—597 doi.org/10.1007/s13668-024-00543-x
European Food Safety Authority (EFSA). The intake of added and free sugars should be as low as possible.
Giussani et al. (2022). Fructose Intake, Hypertension and Cardiometabolic Risk Factors in Children and Adolescents: From Pathophysiology to Clinical Aspects. A narrative review. Front. Med. 9:792949 doi.org/10.3389/fmed.2022.792949
Malik & Hu (2022). The role of sugar-sweetened beverages in the global epidemics of obesity and chronic diseases. Nat Rev Endocrinol 18, 205-218 (2022) doi.org/10.1038/s41574-021-00627-6
Wieser et al. (2020). The Two Faces of Wheat Frontiers in Nutrition, 7, 517313. doi.org/10.3389/fnut.2020.517313
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