Miley Cyrus has been on a fitness kick lately, but a recent photo that she tweeted has some fans thinking she may be taking her regimen a bit too far.

The 'Party in the U.S.A.' songstress posted a photo of her nearly microscopic waist and jutting hip bones, writing, "My 'fiance' jeans. But for real though." Whatever that means, Cyrus' figure is leading many of her followers to voice concern over her shrinking figure. She does look pretty gaunt -- check out her pencil-thin arms -- but some people's natural and healthy weight is just lower than others, and we're not doctors, so we're not about to judge her.

That said, this isn't the first time that the Pilates enthusiast has come under fire for her weight loss. She recently shed quite a few pounds by changing her diet, but she insisted she did so for health reasons, not vanity. She explained, “For everyone calling me anorexic I have a gluten and lactose allergy.”

Cyrus added, “It’s not about weight it’s about health. Gluten is crapppp anyway! Gluten free food is sooo good & healthy!” In a reply to a fan, Miley continued, “Everyone should try no gluten for a week!” she wrote. “The change in your skin, phyisical and mental health is amazing! U won’t go back!”

Also in fairness to Miley, she's been slender for months now. She flashed her abs leaving a Pilates class in April -- and, er, other things while shopping.

Do you think Miley is too skinny? Sound off in the comments!

Watch the Miley Cyrus 'Party in the U.S.A.' Video