effluvium

Sudden hair loss of the type you describe is known as telogen effluvium.

Bariatric surgery or restricted diets can lead to telogen effluvium, in which many follicles let go of their hairs.

“Telogen effluvium short-circuits the cycle for many hairs,” Garza said.

According to Garza, simply managing your stress may be another solution to telogen effluvium.

Some people may never feel like their hair has returned to its previous volume: Doctors said they have noticed that telogen effluvium can occasionally set off other types of more permanent hair loss, such as female- or male-pattern baldness, although they don’t know why.