Paris Hilton's CoStar Nicole Richie is in Rehab

Nicole Richie is too thin for her own good. Socialite Nicole Richie, whose rail-thin appearance in recent photos has stoked tabloid speculation of an eating disorder, has checked into a treatment facility to address her inability to gain weight, her publicist said on Thursday.

"She is working with a team of doctors and specialists whose focus is nutrition," spokeswoman Nicole Perna said in a statement.