Matching weight cutting with athletes' welfare continues to be a serious challenge facing combat sports and Cynthia Calvillo is the latest fighter to address what went wrong when she missed weight ahead of a UFC Fight Night in Argentina.
The 31-year-old cut a distressed figure as she stripped down and jumped on the scales this morning, looking shaky on her feet and needing to be held steady by two women alongside her holding up a curtain.
Calvillo almost stumbled while she was on the scales and was slow to leave when her weight was announced at 118 pounds (53.5kg) — almost one kilo over the limit.
Former and current UFC stars like Brendan Schaub, Cris Cyborg, and Sarah Kaufman were among those taken aback by the shocking scenes.
Late on Saturday afternoon (AEDT) Calvillo released a statement about what happened, saying she got her period and was unable to sweat and shed the remaining weight.
"Basically what happened is I started my period this week," Calvillo told MMA Fighting. "We were kind of prepared for it, because we could feel the symptoms, but unfortunately this morning when we got up it was about 5:30am and I had two pounds to go.
"Then, I couldn't cut any weight at all from 5:30am to 8am. We tried everything and I could not break a sweat.
"Even when I got up to the scale, I was the same weight that I woke up at 5:30 in the morning."
Calvillo's team stopped her from continuing to try and cut weight when it became clear she was fighting a losing battle, not wanting her health to deteriorate any further than it already had.
"They decided to go ahead and stop me from continuing cutting the weight at 9am," Calvillo said. "They didn't want to make me suffer more so that I was still able to fight.
"So, that's basically what happened. Unfortunately, we tried to prepare the best for it, but my body was just not sweating due to having to retain the water because of my period."
Despite the scary scenes on the scales and the calls by some to stop her from stepping into the Octagon, Calvillo's scheduled strawweight bout against Brazilian Poliana Botelho on tomorrow's main card in Argentina will still go ahead. As punishment for missing weight, the American will be fined 20 per cent of her purse.
Calvillo's coach Justin Buchholz said his pupil tried to push through the pain like a "savage" but in the end it was impossible to get her to sweat.
"We're past it all now and we're just focused on the fight. Once we got off the scale I've been keeping her zoned in," Buchholz told mmanytt.com. "She had a brutal cut because she got her period.
"She woke up at 118 pounds, two pounds over. We cut from 5:30am to 9am. We used baths, saunas, a rubber suit, treadmill, bike, but still nothing was coming off.
"She is tougher than me I'll tell you that. She just couldn't sweat. I've been doing this for 10 years at the highest level. It wasn't through a lack of effort or not being disciplined.
"Last Saturday she was just 10 pounds over at 126 (pounds), that's lower than when she fought four times in that year. We seriously did everything possible. That's all I can ask. She did it all like a savage."