Miley Cyrus last year (right) and thinner in December (left). See her now after the jump.

Miley Cyrus, who only a few months ago was touting her voluptuous curves and fuller breasts, now looks shockingly thin. She was spotted leaving a Pilates class in Los Angeles today and her hip bones were jutting noticeably as she walked.

The shocking turn of events comes little more than three months since she Tweeted about her voluptuous curves in defense of her on-again, off-again BFF Demi Lovato.

Lovato, who went through rehab in January a year ago because of an eating disorder and other issues, gained more than 30 pounds after exiting treatment.

She said she felt much better about herself, but drew snarky comments for her weight on the social networking site.

That’s when Cyrus, 19, sprang to her defense. “@ddlovato AMEN! I will destroy any one that ever calls you the F word. You have the SEXIIIESTTTT curvyyyy body! I LOVE IT! #werkthosecurves.”

Since Miley ended her Gypsy Heart Tour, she also appeared to have gained some weight. She told her three million followers that real women have curves and was glad she’s finally getting them.

“@DukeofEarles SO hot! I don’t wanna be shaped like a girl I LOVE being shaped like a WOMAN,” she tweeted. “Trust me ladies your man wont mind either. ;)”

The obvious change in her weight first came to public attention in December, when Miley appeared on the beach in Hawaii and looked noticeably thinner. But she appears to have lost even more weight since then.

Miley looked almost too-thin. Her arms are noticeably thinner, her stomach is washboard flat and her breasts, well, they’ve deflated a bit, too, and her legs are now bird-like.

Some reports say she has been working out obsessively everyday. She was spotted wearing a midriff baring black top with skin-tight leggings.

Miley has been separated from her boyfriend Liam Hemsworth, while he’s been out promoting his new film, “The Hunger Games.” Is it getting to her?

Some reports say she is also jealous of his Hunger Games co-star Jennifer Lawrence. The two have appeared very friendly on their joint promotion tours and had obvious on-screen chemistry in the film.

Miley, however, has been nothing if not supportive. “I think the hardest part for Liam was being away from me,” she said defensively in an interview, before adding, “And his brother and his family and all his friends.”

Miley and Liam began dating on the set of their movie “The Last Song,” in 2009. They split in Aug. 2010, reunited a month later, then split again, before hooking up last year.