Sugar and Sport: How Much Is Allowed
Sugar has long held the status of the main enemy of healthy eating. At the same time, the sports drinks, gels and bars that professional athletes use consist predominantly of that same sugar. The editorial team explains how these two realities are reconciled and how much sugar a person who trains regularly can allow themselves.
What 'free sugars' are
Not all sugar is the same from the standpoint of recommendations. The World Health Organization (WHO, 2015) singles out the concept of 'free sugars' — mono- and disaccharides that manufacturers, cooks or the consumer themselves add to products, as well as sugars naturally present in honey, syrups, fruit juices and juice concentrates.
Free sugars do not include sugars in whole fruit, vegetables and milk. They are 'packaged' together with fiber, water, protein and micronutrients, so they are absorbed more slowly and rarely lead to overeating. That is precisely why an apple and a glass of apple juice are different products in this context.
The WHO strongly recommends limiting free sugars to less than 10% of total calories, and conditionally recommends a further reduction to 5%. For a 2000 kcal diet, 10% corresponds to about 50 g of sugar a day, and 5% — to about 25 g.
The European Food Safety Authority (EFSA, 2022), in its opinion on sugars, was unable to establish a tolerable upper level but concluded that the consumption of added and free sugars should be as low as possible within a balanced diet.
How sugar harms in excess
The main problem with sugar is its energy density combined with low satiety. The meta-analysis by Te Morenga, Mallard and Mann (2013) in the BMJ showed that an increase in sugar consumption is associated with weight gain, and a decrease with weight loss, with the effect explained predominantly by the change in total calorie intake.
Sugary drinks are especially problematic. Liquid calories are almost not compensated for by a reduction in food intake. The review by Malik and Hu (2019) links regular consumption of sugar-sweetened drinks with an increased risk of obesity, type 2 diabetes and cardiovascular diseases.
An excess of fructose, especially in drinks, can contribute to the accumulation of fat in the liver and to unfavorable changes in the lipid profile. Free sugars also remain the main dietary factor in tooth decay, and this applies to athletes, who often drink sports drinks, no less than to other people.
It is important to understand the context: most of these data were obtained in the general population, where an excess of sugar is combined with physical inactivity and a positive energy balance. A physically active person metabolizes carbohydrates differently, but this does not entirely free them from the risks.
When sugar works toward results
During long and intense exertion, fast carbohydrates are not a harmful product but effective fuel. Burke and colleagues (2011) and Jeukendrup (2014) recommend up to 30–60 g of carbohydrates per hour during exertion lasting over an hour and up to 90 g per hour in the longest events.
The study by Currell and Jeukendrup (2008) showed that a mix of glucose and fructose provides better performance in prolonged exertion than glucose alone. This is because these sugars are absorbed via different transporters in the gut, and their combination increases the total rate of energy delivery.
After an exhausting workout, fast carbohydrates help accelerate glycogen recovery, which is important when the next workout or start takes place within a day. For strength workouts lasting up to an hour, the need for sugar during the session is usually absent.
| Situation | Role of fast carbohydrates | Comment |
|---|---|---|
| Endurance over 60–90 min | High | Gels, drinks, a mix of glucose and fructose |
| Two workouts a day | Medium | Acceleration of glycogen recovery |
| Strength training up to 1 h | Low | The usual diet is sufficient |
| An ordinary day without training | Minimal | The general WHO limits apply |
How much is allowed: practical guidelines
The editorial team suggests separating sugar 'by purpose'. Sugar consumed directly during a long workout or competition as fuel has a different physiological significance than sugar from sweets and drinks in everyday life. However, for assessing the overall diet it should still be taken into account.
Practical tips for people who train:
- on ordinary days keep free sugars within 10% of calories, and preferably lower;
- build the base of your carbohydrates from grains, potatoes, legumes, whole-grain bread and fruit;
- replace sugary drinks and juices with water; sports drinks — only during long exertion;
- on a weight-loss diet, sugar is the first candidate for reduction because of its low satiety;
- after sweet sports products, rinse your mouth with water to protect your teeth.
People with diabetes, insulin resistance or an increased risk of these conditions need to coordinate their strategy for consuming carbohydrates during training with an endocrinologist, since physical exertion can both raise and sharply lower glucose levels.
Editorial conclusions
Sugar itself is not a poison, but an excess of free sugars, especially in drinks, is associated with weight gain and metabolic risks.
During long exertion, fast carbohydrates are a tool for increasing performance with proven effectiveness.
The sensible approach is to limit sugar in everyday life and use it purposefully where it provides an athletic benefit.
We also recommend our materials on nutrition on competition day, on fiber in an athlete's diet and on calculating macros for weight loss.
References
- World Health Organization. Guideline: sugars intake for adults and children. Geneva: WHO; 2015.
- EFSA Panel on Nutrition, Novel Foods and Food Allergens. Tolerable upper intake level for dietary sugars. EFSA J. 2022;20(2):7074.
- Te Morenga L, Mallard S, Mann J. Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies. BMJ. 2013;346:e7492.
- Malik VS, Hu FB. Sugar-sweetened beverages and cardiometabolic health: an update of the evidence. Nutrients. 2019;11(8):1840.
- Burke LM, Hawley JA, Wong SH, Jeukendrup AE. Carbohydrates for training and competition. J Sports Sci. 2011;29(Suppl 1):S17–S27.
- Jeukendrup A. A step towards personalized sports nutrition: carbohydrate intake during exercise. Sports Med. 2014;44(Suppl 1):S25–S33.
- Currell K, Jeukendrup AE. Superior endurance performance with ingestion of multiple transportable carbohydrates. Med Sci Sports Exerc. 2008;40(2):275–281.
Andriy Melnyk
A strength-sports coach and author of programs for beginner and intermediate levels. Writes about training planning.
