My friend is anorexic and wants to know if she can play lacrosse?

My friend really wants to play lacrosse, but right now she is struggling with anorexia. If she is able to gain enough weight, heart rate and vital signs are good and her period returns, do you think she would be able to play.
The pre-season starts in three weeks. I don’t want to know if the weight gain is realistic, I want to know if she would be able to just jump right in to running and into a demanding sport??