Reports later confirmed that Hefford suffered from a condition called urea cycle disorder, resulting in a build up of fluid in her brain and ammonia in her blood. The defect, which affects one in 8000 people, prevented her body from breaking down the huge amounts of protein she was eating, chiefly supplements, shakes and egg whites.
The 25-year-old did not know of her condition but the athlete's family said she felt tired and "weird" in the weeks leading up to the incident.
Her mother, Michelle White, told PerthNow: "I said to her, 'I think you're doing too much at the gym, calm down, slow it down.'
"I couldn't believe what the doctors were telling me, she was dying, I said, 'You have to give her more time,' because she didn't look sick, she looked beautiful,"
White also took the opportunity to raise concerns about the dangers of excessive protein intake.
"I know there are people other than Megan who have ended up in hospital because they've overloaded on supplements," said White. "The sale of these products need to be regulated."
Health experts weighed in, suggesting that even without a medical condition, excessive protein supplement intake could be dangerous.
"I think the problem with the supplement industry is that it's really designed to make money for the companies which sell the products and not to provide any significant health benefit for the vast majority of people taking them," said Dr Omar Khorshid, President of the Australian Medical Association WA.
"This case is obviously tragic and illustrates that you may not know you have a health issue that alters the way you metabolise."
If you're going to take supplements, it's important to know any potential side effects. Check out the six protein myths that could be messing with your diet.