Britney Spears stands up against 'out of control' health rumors, posts workout video

Britney Spears wants to put a stop to the rumors.

The singer, 37, returned to social media Tuesday to reassure fans that she's doing OK after many followers voiced worry with a #FreeBritney hashtag on Twitter. .

"Just checking in with all of you who are concerned about me. All is well," Spears said in a video posted to Instagram Tuesday. "My family has been going through a lot of stress and anxiety lately, so I just needed time to deal."

She continued: "Don’t worry I’ll be back very soon."

Later Wednesday, she posted a follow-up video showing her working out with dumbbells and an exercise ball and showing off a few dance moves. She was dressed in a cheery yellow sports bra and yoga pants.

"Who knew stress would be a great 5 pound weight loss," she wrote in the caption. "Yay for me."

Related: Jamie Lynn Spears has a message for Britney’s critics as fans voice concern for pop star

While stars including Miley Cyrus, Steve Aoki and Hayley Kiyoko responded to Spears' post with loving messages, several fans expressed their concern in the comments, stemming from the #FreeBritney movement that has claimed that Spears is being held against her will. 

Concerned onlookers flooded the #FreeBritney hashtag on Twitter following Spears' Instagram post, with one fan claiming that "Britney clearly didn’t write that caption and that generic video message," and another person urging her fellow Spears followers, "Don’t go all soft and believe this!"

Last month, Spears had said she was taking some "me time." 

"Wow! There’s rumors, death threats to my family and my team, and just so many things crazy things being said," she wrote on Instagram Tuesday. "I am trying to take a moment for myself, but everything that’s happening is just making it harder for me. Don’t believe everything you read and hear."

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The #FreeBritney social media buzz was a fan response to reports from outlets like Entertainment Tonight and Variety saying the singer had entered a mental health treatment facility in mid-April. Fans questioned whether Spears, who said she was taking time off for self-care, went there willingly or was forced to by her management and family.

Related: 'Keep Going': Britney Spears' mom, boyfriend offer support after singer takes 'me time'

Spears didn't directly address the speculation, but did promise her fans that she's "doing what’s best at this moment" for herself. 

"You may not know this about me, but I am strong, and stand up for what I want!" she wrote. "Your love and dedication is amazing, but what I need right now is a little bit of privacy to deal with all the hard things that life is throwing my way. If you could do that, I would be forever grateful."

The mother of two received support from her mother Lynne Spears, boyfriend Sam Asghari and younger sister Jamie Lynn Spears after announcing on April 3 that she's taking some "me time."

Spears' time away has further delayed the launches of her Domination residency in Las Vegas and her new album, both of which she postponed to help care for her ailing father Jamie, who had been hospitalized after suffering a ruptured colon. 

Contributing: Maeve McDermott