Hilary Duff Bends Over Backwards to Stay in Shape

Hilary Duff is an actress, singer, author, and … contortionist!

During a sweat session on Tuesday, the 25-year-old showed just how flexible she is, nearly bending over backwards while doing an intricate piloxing move.

“Nice stretch,” Duff wrote on Twitter, along with a photo of herself doing a gravity-defying handstand-type move in which her legs rested in stirrups over her head while her trainer supported her with her feet. In a second photo, the star stretches out on a Pilates machine, nearly doing a split. “Working hard with my girl Viv,” Duff noted. “Piloxing kicking my butt!”

[Related: Hilary Duff: I'm "Working Hard" to Lose the Baby Weight]

Piloxing – which is described as a “non-stop interval fusion of standing Pilates, boxing, and dance” – is just one of the get-fit secrets Duff has used to regain her pre-baby body. Recently, she’s also tweeted about taking a late-night spin at SoulCycle, stretching it out in a yoga session, and getting her sweat on in “a burn class called ex-flosion.” She’s also been slurping down green smoothies, which she whips up for herself and now for her son Luca, who will turn 1 in March.

All her hard work at the gym has paid off. In November, she happily blasted out the news that she was back to her old size and credited another trainer she is working with for helping her lose weight. “Yaaaa bitches,” tweeted the clearly excited star. “Gabe Johns your kickin my ass and its paying off! Skinny jeans! LETS GO!”

Along with the tweet she posted a photo of her size-26 Rag & Bone jeans.

Unlike most celebrities, Duff took her time dropping the baby weight – and that was just fine with her.

"There are some women who look the same right after – I think they are freaks of nature! I don't know how that happens,” she told Parents in October. “I'm not one of those people. It takes your body nine months to get there – really 10 months. So I'm trying to be patient but I'm working hard. And I think now more than ever, I appreciate my body and what it's done for me.”

[Related: Hilary Duff and Luca Share a Royally Sweet Moment]

And don’t expect Duff to follow on the same path as Jessica Simpson, who returned to her pre-baby size and immediately became pregnant again. The one-time “Lizzie McGuire” star is in no rush to expand her family. In fact, she and her husband, retired NHL player Mike Comrie, may remain a party of three forever.

“Mike and I are literally obsessed with Luca,” Duff told “Access Hollywood” in December. “We’re like, ‘He’s perfect. We should just be one and done. But I think once your baby starts getting older, you miss that phase and you go in for round two.”

For now it’s rounds of sweat sessions – and they sure do the body good!

More Celebrity Features on Yahoo!:

Follow omg! on Twitter