Chistyakov had recently spent time in hospital for an operation, and explained a friend's death had motivated him to improve his health.
"I'm starting to train, and I will try to lead a more healthy lifestyle," Chistyakov said after the fight.
"I'll tell you, a man died today — my friend, a blogger. He weighed 190kg. Please Lord, all people, take care of yourself.
Recounting the fight, Chistyakov said: "I lay on her back, but she did not fall, and then I didn't know what to do."
Footage of the bout went viral on social media, and former UFC fighter Julie Kedzie congratulated Mazdyuk for her bravery.
"It takes a certain kind of bravery to fight that last bout, and I sincerely hope it gets funnelled into a career that makes her bravery universally applauded," Kedzie said.
But not everyone was impressed by the spectacle, with UFC referee Marc Goddard labelling it a "sickening" ordeal.
"This is what we are dealing with – in 2020," Goddard said.
"This is what we are fighting against as the parallels and negative connotations are continually drawn.
"To outsiders and detractors, this is MMA. Shameful. Sickening. Abysmal."