LATEST: Troubled pop star Britney Spears has been suffering from bulimia since she was 16 years old, according to US reports. The TOXIC star reportedly told doctors at rehab facility Promises in Malibu, California about her eating disorder after she was forced to examine her unhealthy lifestyle. A source also tells American publication the Star the 25-year-old has been diagnosed with mental health problem bipolar disorder - manic depression - but her eating disorder is hampering her recovery. The source explains, "She is on medication for bipolar disorder, but the pills are not staying in her system because she is bulimic and is throwing them up before they can help her." "(In the past) she'd pig out on junk food, chips, candy, cola and ice cream, and then she'd feel so guilty, she'd make herself throw up. The only thing that made her stop was when she got pregnant."