Hair today, gone tomorrow. Hair styles and trends come and go — the worst ones aggravate your hair’s health and cause more strands to go down the drain. While influencers insist one trend in particular just takes time to adjust to , experts warn it could actually backfire and lead to thinner and grayer hair. Referred to as #nopoo , the “hair training” trend has been growing in popularity on social media and among Gen Zers. The idea is to avoid shampoo to train your hair and scalp to be