Lady Gaga has been accused of having a serious drug problem by celebrity biographer and investigative journalist Ian Halperin.

From heroin to cocaine and ecstasy, her friends say that she has done every drug conceivable. You name it she has done it, Halperin said in an interview with Star magazine.

She's morphed into this caricature called Lady Gaga, who isn't even a real person. The girl known as Stefi to her friends and family has all but disappeared.

Gaga has admitted that she had a cocaine problem in the past, but claims to have kicked the habit.

She has publicly stated that she used to do bags and bags of cocaine while listening to The Cure.

But I was able to stop, because I was panicking more on the drugs than I was sober. So I'm fine now, Gaga commented.

Lady Gaga might be strange, but she was born that way, right? Or is it really that she has fallen off the wagon and has returned to a drug habit that plagued her earlier years performing?

Or, is Halperin just  trying to stir up scandal to promote his new book on the pop-music queen?

Halperin also claims that the singer is unhealthy and obsessed with weight loss to the point of anorexia.

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, Halperin told Star 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, analyzing and critiquing her body. It's an unhealthy obsession.

Halperin spent a year writing his book on Lady Gaga. He has also penned biographies on Michael Jackson, Brad Pitt and Angelina Jolie.