The 30-year-old posted a heartfelt message insisting that her focus was looking after her two sons, Bobby, three, and three-month-old Harry — and not worrying about her figure.
Jennifer also shared a picture of herself with her two beautiful boys, taken in the hospital shortly after Harry's arrival.
"To all the horrible ppl commenting about my weight… I gave birth 12 WEEKS AGO! Sort ur heads out, my baby boy is my priority NOT my size!!
And just for the record I'm the luckiest, happiest woman in the world with two boys to die for so 'ALL THE BEST!' to you!!!x"
She later added, "And when I'm back to a size 8 with two amazing kids you'll still be sat in ur computer chair bitter and twisted!! #sosad."
Jennifer recently opened up about her experiences with postnatal depression following the birth of her first son.
Speaking on Daybreak with hosts Lorraine Kelly and Aled Jones, she explained, "There was a kind of baby blues that never went away, and it was only that I was very lucky that my mum had suffered with it that she saw the signs straight away, so my postnatal depression was treated pretty quickly.
"But there's so many women out there who are suffering with it and there's such a stigma attached to it."
Jennifer went on to say that it's hard for women to admit they have depression when they are constantly faced with ideals of how their life should be.
"If you only look at adverts on TV, we're programmed to think that this is the most special time in you life and you're going to have this instant bond and this instant connection," she said. "And for some mums it just doesn't happen, and then they feel that they're a failure."