Common sports nutrition myths

Sports nutrition is a field where genuine science and persistent myths coexist uncomfortably closely. Some of the most widely held beliefs among endurance athletes are not supported by evidence. This article addresses the most common myths directly with a brief explanation of what research actually shows.

Myth 1: Fasted training burns more fat

Partially true but incorrectly applied. Fasted training increases fat oxidation during the fasted session. However, the key metric for endurance performance is not fat oxidation during training—it is carbohydrate availability during competition. Chronic fasted training does not significantly increase fat oxidation rates at competitive intensities above approximately 65% of maximal aerobic capacity. At competitive intensity, carbohydrates are the dominant fuel regardless of the training state. Fasted training has a role in periodized nutrition strategies, but it does not replace quality training fueled by carbohydrates.

Myth 2: Gels cause stomach upset

Gels themselves do not cause stomach upset. Too much carbohydrate too quickly, with too high an osmolality and insufficient hydration, causes stomach upset. Most standard gel products have an osmolality of 500–1200 mOsm/kg—clearly hypertonic—and are consumed in bolus doses of 20–25 g at once. This combination, especially without water, is a significant gastric stressor. Well-formulated products with lower osmolality, consumed in appropriate doses with sufficient hydration, do not cause the discomfort associated with consuming standard gels.

Myth 3: Sports drinks are better than gels for long events

Neither is categorically better. The choice depends on the intended use. Sports drinks deliver carbohydrates and hydration in a single system, simplifying logistics in shorter events. In long events where carrying weight matters and intake needs to be continuous rather than quantity-based, a concentrated gel system separate from hydration provides better control over both variables. The most concentrated sports drinks deliver 16–20 g per 100 ml; concentrated gel systems deliver 60–80 g per 100 ml. For high carbohydrate delivery per gram carried, concentrated systems are superior.

Myth 4: You need to drink eight glasses of water a day

This recommendation has no scientific basis for any individual. Hydration needs depend on body size, activity level, climate, and diet. Athletes who sweat a lot require significantly more than eight glasses. Someone with low activity in cool conditions might need less. The correct approach is to monitor urine color (pale yellow = adequate) and drink according to thirst outside of training, and to follow scheduled hydration during exertion, where thirst attenuation is a factor.

Myth 5: Protein supplements are essential for endurance athletes

Most endurance athletes can meet their protein needs through food without supplements. The evidence-based range of 1.4–2.0 g/kg/day is achievable with a normal diet that includes animal or plant protein at each meal. Protein supplements are useful when food timing is difficult—immediately after exertion, when appetite is suppressed, and whole food intake is limited. They are not essential for athletes who can consume sufficient protein at appropriate times.

Myth 6: Carbohydrates make you fat

Carbohydrates alone do not cause fat storage. Excessive energy intake—from any macronutrient—relative to expenditure leads to fat storage. Athletes with high training loads typically require a high carbohydrate intake to support training volume and recovery. Reducing carbohydrate intake below training needs leads to impaired performance, poor recovery, hormonal disruption, and an increased risk of injury in athletes. For endurance athletes in heavy training, adequate carbohydrate intake supports body composition goals better than carbohydrate restriction.

Myth 7: The harder you train, the more supplements you need

Supplements fill gaps that food leaves. Hard training increases the need for energy, carbohydrates, protein, and some micronutrients. If food intake scales with training load, most supplement uses are unnecessary. Exceptions—iron for runners with documented deficiency, vitamin D in Nordic winter conditions with limited sunlight, creatine for specific strength training goals—are targeted interventions for specific deficiencies or applications, not general requirements for a hard-training athlete.

Myth 8: If a product works for elite athletes, it will work for you

Elite athletes use products under training and competition loads that recreational athletes do not approach. Their gastric tolerance, absorption capacity, and physiological responses have been shaped by years of structured training and gut adaptation that recreational athletes have not undergone. A product that an elite athlete consumes at 90 g/h in competition can cause significant gastrointestinal distress for a recreational athlete who has not done gut training. Product evaluation should be based on one's own physiology and training status, not on what elite athletes use.

References

Burke LM, Ross ML, Garvican-Lewis LA, Welvaert M, Heikura IA, Forbes SG, et al. (2017). Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. Journal of Physiology. 595(9), 2785–2807.

Thomas DT, Erdman KA, Burke LM. (2016). Position of the Academy of Nutrition and Dietetics, Dietitians of Canada, and the American College of Sports Medicine: nutrition and athletic performance. Journal of the Academy of Nutrition and Dietetics. 116(3), 501–528.

Jeukendrup AE. (2011). Nutrition for endurance sports: marathon, triathlon, and road cycling. Journal of Sports Sciences. 29(Suppl 1), S91–S99.