A new explosive book has accused pop superstar Lady Gaga of starving herself for weeks at a time to fit into her tiny costumes and experimenting with every drug under the sun.
The book written by investigative journalist Ian Halperin accuses the 'Paparazzi' singer's dangerous dieting as "sick".
Halperin told Star magazine the New Yorker is losing touch with reality, saying she is turning into a caricature of herself and not the 'Stefi' her friends know.
"Those who have worked with her on tour reported to me that Gaga barely ate for weeks at a time to fit into her costume," the Daily Mail quoted him as telling the magazine.
"She is sick and obsessed with her weight. One friend told me, Gaga will stare at herself in the mirror for hours on end, analysing and critiquing her body. It's an unhealthy obsession," he said.
Halperin also shed light on her use of narcotics, with accusations that "her drug use started young".
"From heroin to cocaine and ecstasy, her friends say that she has done every drug conceivable. You name it she has done it," he said.
Halperin, who has written biographies of Michael Jackson, Brad Pitt and Angelina Jolie, spent 12 months writing his tell-all book.
He said Gaga's outfits and heavy make-up are not just for spectacle - they help to disguise her illness.