The 41-year-old, who gave birth to her fifth child River Rocket in August 2016, shared a photo of herself trying on a pair of striped trousers.
“Finally ‘almost’ fitting into these gorgeous trousers, so comfy post little baby and beyond,” she wrote.
But one commenter felt Oliver’s focus sent out the wrong message to other new mums.
“I am currently pregnant with my second baby,” they wrote. “Every minute of every day I’m scrutinising my weight. Pictures like this by naturally slim women do not help!
“Shouldn’t you be more concerned about bonding with your child rather than how quickly you fit back into your jeans?”
Oliver decided to defend herself, claiming the post was “not about the trousers”.
“For God sake I still have heaps to lose, my t-shirt hides a lot,” she responded.
“It was merely a shout-out to the lovely girls who sent me the trousers nothing more I hardly ever put pictures up of myself and certainly not a ‘selfie’.
“I am confident with my body before, during and after pregnancy and totally get that things don’t go back to normal for at least six months to a year, if at all and after five babies, I should know.”
Oliver added: “As for bonding with my baby... I feel no need to address this it’s ridiculous.
“So please next time if I irritate you just unfollow me it was just meant to be a nice pic of a pair of good trews.”
After Oliver replied, fans began commenting on the photo defending her.
“It’s her Instagram, she can’t post what ever the hell she likes,” one person wrote.
“She’s proud of herself. She shouldn’t have to not post photos because she might upset a few women who haven’t bounced back yet!”
In a blog hosted on The Huffington Post UK, personal trainer Jacqueline Hooton, wrote:
“Slim women are often accused of being self-absorbed, obsessive, eating like a rabbit or in Jools’ case not bonding with her child and failing to help other women.
“The implicit suggestion being fatter or at the very least not flaunting her thinness would be a major contribution to womankind everywhere.
“Can we please stop this double standard? Attacking thin people and making assumptions is just as bad as attacking those overweight and referring to them as lazy, lacking in self-control or undisciplined.
“The reasons people are thin are as varied as those who are more generously proportioned.”
Oliver gave birth to her fifth child on 8 August 2016. She and Jamie Oliver are also parents to Poppy, 14, Daisy, 12, Petal, six, and Buddy, five.