Lady Gaga was hospitalized six times in 2009 with the ill-effects of a string of drastic diets, according to her former tour manager.

David Ciemny, who worked for the superstar from 2008 until last year, has gone public with his shocking claims in new book Poker Face: The Rise and Rise of Lady GaGa, by Maureen Callahan.

He alleges the outrageous singer went on crash diets after junk food binges and even lost 20 pounds between the first and final fittings for a show outfit.

Ciemny says, "When I say she was sick, I mean physically and mentally."

Talent scout Wendy Starland adds, "The pressure on her to lose weight was very high."

The book is set to hit shelves on September 14.