Lady Gaga and Dangerous Dieting: Is She Hiding an Eating Disorder?

(CBS) If Lady Gaga's former tour manager is to be believed, America's favorite musical fashion queen is suffering from a serious eating disorder and was hospitalized at least six times in 2009.

"When I say she was sick, I mean physically and mentally," David Ciemny claims in a new unauthorized tell-all "Poker Face: The Rise and Rise of Lady Gaga," according to RadarOnline.

The book, written by New York Post veteran reporter Maureen Callahan, interviewed 50 "friends, employees, rivals, and music industry veterans," to try and get a fuller picture of the outlandish performer who grew up as Stefani Germanotta, an awkward teen.

Ciemny also "recalled being on tour with Gaga and said she would binge on sweets and unhealthy food, then not eat for weeks to fit into her costumes - one time losing 20 pounds between fittings," reports Radar.

No word from Gaga's camp yet on the accusations, but whether or not the celebrity is suffering from an eating disorder, millions of young women are.

The most common eating disorders are anorexia (relentless pursuit of thinness), bulimia (eating huge amounts of food then purging it) and binge eating (eating huge amounts of food without purging).

According to the National Institutes of Mental Health (NIMH), 85 to 95 of anorexia and bulimia sufferers are female. And the disorders can be deadly.

"According to some studies, people with anorexia are up to ten times more likely to die as a result of their illness compared to those without the disorder," says the NIMH. "The most common complications that lead to death are cardiac arrest, and electrolyte and fluid imbalances. Suicide also can result."

Depression and trauma are often, but not always, at the root of the disorders. And many people will go to great lengths to hide it. If you think someone you love might be at risk, find out about the secret signs.