A source close to Lindsay Lohan has told US Weekly that the actress has been popping the prescription drug Adderall, commonly used to treat attention deficit hyperactivity disorder, to lose weight.

“She takes Adderall all the time,” one source told Us. “She gets jittery because of the way the pills affect her. It’s a major reason why she’s losing weight.”

That, along with the stress from her recent messy relationship troubles, her excessive partying and general lack of health consciousness, would explain why she’s shocked so many people lately with her gaunt appearance in bathing suits in Hawaii.