On average, a typical human sheds 50 to 100 hairs a day. Though it differs for everyone, someone experiencing telogen effluvium might lose up to 15% of their hair. In a 2021 study published in the National Library of Medicine, 75% of the 112 women who underwent sleeve gastrectomy experienced hair loss. Among them, 80% reported that the thinning started three to four months following their weight loss procedure. Bariatric surgery can lead to hair loss. But there isn’t an exact amount of hair you can expect to lose. Consult your doctor if your condition worries you, is worsening, or isn’t going away.