I would guess that underweight women might suddenly have an excess of testosterone on keto, when they go low estrogen and stop cycling, especially if they have symptoms they are trying to fix before-hand like pcos which is about androgens anyways.

and we all know that suddenly testosterone filled (male) teens have stinky feet and need to be taught about deoderant etc.

It could happen.

I wouldn't be surprised if this goes along with a sudden super high libido, like even to the point of problematic behavior, like a typical lady might suddenly be "on the prowl".