Insiders say Demi Moore is "insanely" obsessed with being thin and staying young -- even by Hollywood standards. A so-called pal says her daily diet has been "Red Bull for breakfast. Red Bull for lunch. Red Bull for dinner, with a lettuce leaf and a tablespoon -- yes a tablespoon! -- of tuna fish thrown in... That's it." Another source says, "Demi got so she'd almost talk about nothing else than finding ways to keep young and pretty... For a long time, it was clear she was doing it all to keep Ashton interested. Then, when she found out about his cheating, her world really spiraled out of control."

Much like his album Take Care, Drake's "The Motto" featuring Lil' Wayne has gone platinum for sales of a million copies. It has also jumped up five spots on the Billboard Hot 100 pop chart, checking in this week at number-16.

Lindsay Lohan says there's NO TRUTH to reports she was boozing at a SAG Awards after party this weekend ... and now, TMZ has learned, she's threatening to SUE the media outlets that published the story in the first place. A source close to the actress tells TMZ ... Lindsay is already exploring her legal options with her attorneys ... because she feels the false stories are sabotaging her effort to save her career. Lindsay acknowledges she WAS at the party at the Chateau Marmot hotel in Hollywood Sunday night ... but insists she was sitting with Alan Cummings the whole time and ONLY drank water. We're told Lindsay's also pissed over reports about a recent gas station makeout session with Dennis Hopper's son Henry (pictured above), where she allegedly purchased Red Bull and vodka. Sources close to LiLo tell us the actress is adamant the two are just friends ... NEVER MADE OUT ... and the only items she bought were soda, chips, and cigarettes

Demi Moore hasn't only been doing whip-its -- she's been trying to do Zac Efron. According to Us Weekly, the 49-year-old has been on a "desperate spiral" that included wild parties, drug use and young men. An insider says Demi has been "really down" since splitting with Ashton Kutcher and "she's surrounding herself with young people to make her feel better." And Demi's favorite youngster to party and flirt with is her daughter Rumer's pal Zac Efron -- who is 24, nine years younger than Ashton. She once "tracked down" the High School Musical star at a party in L.A.'s Venice neighborhood. "She seemed out of her mind at this party," a source said. Demi collapsed and was hospitalized last month after reportedly doing whip-its.