New York, July 8 : Mischa Barton has raised eyebrows after packing on the pounds, with her friends laying the blame on the actress' hard partying ways.

The O. C. star, who left onlookers gasping with her dramatic weight loss six months ago, was said to have replaced her previously thin frame with some serious expanding curves and a bloated face.

And sources alleged it's the doing of the 23-year-old's heavy partying and recent split from The Kooks singer Luke Pritchard.

"When her love life is out of sorts she just lets herself go and hits the party scene. Her friends try to tell her to stop but she doesn't listen. Drinking bloats her terribly," the New York Daily News quoted a source as telling Closer magazine.

The source added: "After clubbing she'll usually tuck into greasy fast food. She'll starve herself all day then binge on junk. It wreaks havoc with her system."

But a story in the Daily Mail suggested that Barton's puffy appearance stemmed from a bad reaction to antibiotics treating a recently pulled wisdom tooth. (ANI)