Why? Because it turns out the Keeping Up With the Kardashian's star was obligated to ditch her summery blond 'do for her Vogue magazine cover!
The 33-year-old stunner's hair colorist, Tracy Cunningham, took to Instagram to caption one of the iconic photos shot by Annie Leibovitz while dishing the deets of Kim's hair makeover in preparation for her Vogue cover with fiancé Kanye West.
"Now I know why @kimkardashian needed to go back to her natural #brunette! She told me it was top secret and I would know soon enough! So cool @voguemagazine #ilovemyjob #kimkardashian#kanyewest #redkenready Thank God for #shadeseq(The color that thinks its a conditioner) for Shiny,Silky and Healthy Hair!," she wrote.