Kim Kardashian West has to bleached hair has taken over "13 hours" to complete. (Pic: Bang Showbiz)

Kim Kardashian West has to bleach her hair "in stages" to prevent it from falling out, and so far it has taken over "13 hours" to complete.

The 37-year-old reality star has undergone another beauty overhaul as she has dyed her hair platinum blonde, but the 'Keeping Up With the Kardashians' star has revealed she spent over "13 hours" carrying out the makeover, and the stylist had to gradually colour her locks so her hair did not "break off".

Speaking about the process on Twitter, Kim - who has four-year-old daughter North, as well as two-year-old son Saint with her rapper husband Kanye West, and is expecting her third child via a surrogate - wrote: "#NewProfilePic

"Spent the last few days bleaching my roots (we do it in stages so it doesn't break off). OMG 13 hours & still going. (sic)."

Kim has admitted she has found going blonde "very high maintenance", but she is grateful for her hairdresser Chris Appleton for persevering to get her hair done. 

She added: "This blonde is very high maintenance. Love you @ChrisAppleton1 but getting over this. (sic)."

The reality star has had a busy few weeks as she has recently expanded her KKW Beauty range and added a range of Ultra Beam highlighters, as well as glitter lip glosses, and a trio of fragrances to her label.