bigorexia

noun

big·​orex·​ia ˌbi-gə-ˈrek-sē-ə, -shə 

: muscle dysmorphia

Most American men would do well to exercise more and improve their diets, but a small number … suffer from a condition psychiatrists call bigorexia, or muscle dysmorphia, in which they feel crippling shame and embarrassment about their perceived smallness.

—Rebecca Keegan, The Los Angeles Times