Serena Williams is looking trimmer than ever these days—and fans think they know the reason why.

Commenters on the legendary athlete’s most recent Instagram posts noted the 43-year-old mother-of-two’s noticeably slimmer frame, with many speculating that a medication like Ozempic might have had something to do with her weight loss.

In a video posted earlier this week, Williams danced for the camera wearing a short black tennis dress and neon green shorts, showing off her toned legs.

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While some fans applauded her “slight twerk” and “sashay,” others couldn’t get over her appearance.

“That Ozempic weight loss medicine ain’t no joke,” wrote one person.

“Ozempic?” asked another.

“Poor baby, What happened,” a third commenter wanted to know.

Fans similarly reacted to another pair of photos shared on Instagram which showed Williams snuggled under a blanket on a plane, even though she was snacking on what appeared to be a sandwich in one of the pics.

Related: Serena Williams Addresses “Ridiculous” Appearance-Altering Accusations

“She losing a lot a weight?” one social media user asked.

Others came to the tennis icon’s defense, however.

“nothing wrong with that…everyone is trying to lose weight. I lost 34lbs so far. Not a bad thing. Happy for her,” shared someone else.

Williams has been open about her weight loss journey since welcoming her second daughter, Adira River, with her husband, Alexis Ohanian, in August 2023. They also share a 7-year-old daughter, Olympia.

In May, Williams shared a video of herself trying on a denim skirt that she’d been hoping to fit into for some time.

“I am going to try on my skirt again to see if it’s any closer than it was four weeks ago. Really it’s been about six weeks. Honestly, I feel like it’s gonna fit the same because I’ve been gym-ing a lot but I don’t know if the needle is moving,” she said in the clip, adding, “I wanna cry, but I’m not. I’m gonna stop eating all those snacks,” she joked.