While cutting weight to prepare for the amateur martial arts event, Jessica Lindsay collapsed during exercise due to a lack of fluids.
The 18-year-old was rushed to hospital before passing away four days later.
Although an inexperienced fighter, Lindsay had been cutting weight to meet the 64 kilogram guideline. Just one day before the scheduled bout, her body gave way.
Speaking to 9NEWS, Dr Joe Kosterich suggests that heat exhaustion may have been the final cause.
"There is a point of no return, it is quite extreme and it goes beyond dehydration," says Kosterich. "it is what some would call heat exhaustion or heat shock."
Lindsay's death will be investigated by the coroner.
This article originally appeared on Men's Health.