Under-fuelling and over-training: the effects and impact on the health of athletes

With the recent increase of media reports on athletes risking their health by 'under-fuelling' we asked Professor Stewart Cotterill, our Head of School of Psychology, Sport and Physical Activity to help us understand what under-fuelling means and the effects this has on athletes.

Professor Stewart Cotterill
Professor Stewart Cotterill
Head of School of Psychology, Sport and Physical Activity

Under-fuelling can be a result of a deliberate behaviour, such as trying to reduce body weight or percentage body fat. However, it can be an unconscious by-product of other training status changes. For example, athletes develop specific routines regarding eating and calorie consumption which can be very difficult to change. Decisions to change training volume and training load often take place in the training context without considering the impact these decisions have on dietary needs including essential vitamins and minerals as well as energy intake. These dietary deficiencies can have a significant impact on mental health and psychological functioning. Side effects can include: irritability, tiredness, headaches, reduced ability to concentrate, restlessness, poor sleep, emotional instability and depression.

As a result, nutrition expert support should be a key part of the wider support team working with athletes, and in particular endurance athletes like cyclists, runners, and triathletes. As well as in other sports where athletes are treading a tightrope in terms of functional weight including: gymnastics, boxing, martial arts, and racing jockeys.

Athletes can also have a tendency, in terms of energy expenditure perceptions, that is opposite to many members of the public. For many people they over-estimate the calories they have burned and under estimate the calorie content of their food. Athletes tend to under-estimate their calorie expenditure when training, and as a result underestimate their nutritional needs.

Finally, under and over-eating can, as a form of self-harm, be a symptom of a mental health condition. So, the under-fuelling itself could well be a symptom of a further underlying concern.

Discover more about our health science courses, with a variety of courses in the subject areas of sport, exercise and health science as well as psychology. Or, if you're a budding athlete, check out our Sport Performance Centre and the services available.