If you’re having significant hair loss there’s no replacement for going to your doctor. A lot of the time it isn’t related to things like IF, it’s a coincidence – I got alopecia completely out of the blue, no life changes at the time, nothing. If you live in the kind of place where you start with a specialist, dermatology is your first stop.
I was already loosing my hair ( genetic) but a year of hard-core cutting and IF accelerated my loss. I decided I’d rather than be bald than fat, and definitely rather bald than almost bald and fat. Shaved what remained of my costanza cut and never looked back.
That being said, malnutrition is dangerous, talk to your DR.