Here it is in a nutshell. I see everyone saying that people like Hassan MUST be doping. Guess what, she isn't. She is just willing to take her body to places that others are not. She's not tougher than anyone, she just wants it more and is willing to do what it takes to get it, no matter how destructive it is. It's common knowledge why Salazar has these women on so many supplements. They ALL train so hard that they lose their periods. Losing your period doesn't mean that you are starving because it's not all based on calories and nutrition. A person can be getting enough calories and nutrition to support their running, but not enough to support reproduction and the body senses that and adjusts. Without menstruation, they attempt to replicate this with thyroid medications, birth control pills, $hit loads or calcium, iron and other supplements. Most women back off when they lose their period, that's what their told to do and what any doctor would have them do. Those who want to be the best in the world, keep training and supplementing, training and supplementing, lather rinse repeat. Obviously this carries some pretty hefty consequences down the road, but that's not what they are thinking about. Osteoporosis and infertility may be something they are willing risk for a shot at Olympic gold.
Everyone has choices.