Even the most physically fit moms know how hard it is to shed those extra pounds post-baby.

And while jaws dropped after seeing royal mom Kate Middleton bearing her sculpted abs three months after giving birth, now there's a new mom creating backlash after posting a picture of herself on Instagram just three days after giving birth.

Caroline Berg Eriksen, wife of soccer player Lars-Kristian Eriksen, has the biggest fitness blog in Norway. She says she posted the controversial photo showing off her chiseled body and washboard abs with the caption, "I feel so empty," because she missed her baby bump.

"During the pregnancy, people kept telling me that my body will never be the same and I wanted to show everybody that's not entirely true," Berg Eriksen, 26, told ABC News.

Berg Eriksen says she was amazed at how fast her body bounced back after gaining 22 pounds.

"Right after birth, like three minutes after, I felt like myself again," she said.

But now this picture has started a firestorm online, with one woman writing, "This can't be true," and another saying, "I just think it is absolutely inconceivable that we are of the same species."

"I think we need to put this all on a spectrum and realize that we should applaud the women who look great," said ABC News Senior Medical Contributor Dr. Jennifer Ashton. "But we shouldn't bash the women who can't achieve that."

'Fit Mom' Defends Controversial Photo: 'I Never Called You Fat'

This isn't the first time a post-baby picture has started an online uproar. Mother of three Maria Kang, known as the "Fit Mom," found herself playing defense after catching heat from moms for posting a picture of herself with her three young children with the caption, "What's Your Excuse?"

"Maria was very much in your face," said editor at The Stir, Erica Souter. "She meant it as a motivational tool. It came off insulting. Caroline was all about celebrating herself."

Though Berg Eriksen says she hasn't worked out since giving birth, she says the purpose of the picture wasn't to be cruel.

"I think all women should be proud of themselves, regardless of how they look after labor," she explained.