In the world of Harry Potter, the boy wizard undergoes two magical biological transformations: eating Gillyweed to grow gills and drinking Skele-Gro to repair broken bones.
Students from the University of Leicester in the UK and and McMaster University in Canada have put these medical practices to the test - and concluded that they are not scientifically feasible.
In Harry Potter and the Goblet of Fire, Harry consumes Gillyweed, which allows him to breathe underwater by causing gills to grow on his neck.
Taking into account the oxygen content of the Black Lake and the maximum oxygen use of swimming, they then examined Harry's weight, suggesting that if he had a normal body mass index (BMI) and the average height of a 14 year old boy, he would need to process 443 litres of water at 100 per cent efficiency per minute for every minute he was underwater.
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This would mean the water would have to flow at 2.46 metres per second - twice the velocity of normal airflow and therefore far faster than he could inhale and exhale, causing him to suffocate.
After his broken bones are removed, the matron Madam Pomfrey then gives Harry a dose of Skele-Gro, used for growing bones that are missing.
Students aimed to find how the rate of normal bone growth compares to this accelerated growth, and how much energy Skele-Gro would need to provide in order to rebuild Harry's broken arm.
Observing the timings in the chapter in which Harry is hurt, the students suggest he is healed within the space of 24 hours, Skele-Gro must have accelerated restorative properties.
Skele-Gro should have the capacity to supply the additional 133,050 kilo-calories worth of energy required by the body to regenerate bones without causing any negative side effects - a power output of 6,443 Watt.
The students concluded that Skele-Gro must indeed contain unexplained magical properties that allow it to hold such a vast amount of energy and apply it in a short period of time.
The research was published in the Journal of Interdisciplinary Science Topics.