Best friend owned a high end salon in Dallas. She (and then my doc), told me that the need is to keep the protein up, and make sure you are getting your daily vitamins. The hair loss is the body response to starvation/malnutrition. Biotin can help stronger sprouts of hair come back in. The Rogaine, etc. type of treatments are to get your bald head healthy for hair growth, but it will not stimulate hair growth. There is a difference. BF said that stylists will want to sell the shampoos, protein treatments, etc., but if they haven't experienced or researched this unpleasant and shortlived phenomena of WLS, then they are just pushing products.
I started 5000 mcg Biotin daily. Right on target, at three months, I noticed more hair coming out in my brush and hands when washing my hair in shower.
So, that is my two cents worth. *sigh* I'm gonna watch my protein, take my vits and biotin, and welcome each new little stubby hair that comes back in.