Shampoo is acidic and lowers the ph of your hair that's why it's horrible & knotty if you don't condition afterwards, the cuticles are all raised from the acidic shampoo, then we apply conditioner which is alkaline which restores the hair to it's natural ph & closes the cuticle, resulting in knot free shiny hair, It doesn't make you have thicker or thinner hair, the hair is probably just bushier after shampoo because the cuticles are still raised.