Lindsay Lohan 'Taking Weight Loss Drug'

Lindsay Lohan's skin and bones physique is the result of taking Adderall, it's claimed.

The prescription drug is normally used to treat deficit hyperactivity disorder but weight loss can be a side affect.

"She takes Adderall all the time," a source tells Us magazine. "She gets jittery because of the way the pills affect her.

"It's a major reason why she's losing weight."

But despite flaunting a scarily skinny frame as she frolicked in a bikini during her recent Hawaiian mini-break with her family, Lindsay insists she's healthy.

"I've been eating enough," she tells E! News.

"We're a tight family. We've been through a lot so we take care of each other...We went hiking and everything in Maui, so it was really good."

See Lindsay's skinny dip below