But eagle-eyed fans were quick to point out that Chyka, who left the Housewives after season three, looked a lot heavier set in her mid-section than usual.
"I think somebody has been using the photoshop on poor Chyka," one fan commented on the Instagram photo.
"Lydia this is so rude," said another.
"Dying at the photoshop. Poor Chyka doesn't deserve an extra 47kg Lydia."
Lydia denied claims she'd edited Chyka to look wider around the stomach area, despite fans finding the original image which showed the mother-of-two looking more herself.
"It's an old photo from season 2 no photoshop, I wouldn't do that after being fat shamed myself," she commented back.
But Lydia's followers weren't buying her explanation, saying everyone in the photo had been doctored except for her.
"It is definitely photoshopped. Look at Pettifleur's coat, that is now how that outfit sits. I love all these ladies but Lydia that is definitely not the original," one follower said.
"The fact you're denying it's been photoshopped is hilarious," said another.
Others pointed out that it's visible where the photo had been "blurred and distorted".
"I don't think you did it to fat shame but it's been poorly photoshopped and edited and you've given all these ladies a bad image and treated your followers like idiots by telling them it's not edited," a graphic designer commented.
Lydia and Pettifleur appeared to have their stomachs cinched in the middle, causing Chyka to look wider, while Janet seemed to be the only housewife in the photo to be left untouched.
Filming for the long-awaited fifth season of Real Housewives of Melbourne wrapped last week following prolonged delays due to COVID-19 outbreaks in the city.
"The changes of this world caused me to pause and re-evaluate my life," Lydia wrote on Instagram in April.
"I will miss the camaraderie the interaction with viewers and the challenges that my fellow cast members presented."
Gina also took to Instagram to announce her departure from the iconic reality show.
"An extra big thank you to all my gorgeous followers who have travelled through the last four glorious seasons of #RHOMelbourne with me and made it the most enjoyable ride," she wrote.
Newbies businesswoman Simone Elliott, mother-of-three and yoga instructor Cherry Dipietrantonio, “Champagne Dame” Kyla Kirkpatrick and news anchor Anjali Rao will join the cast for season five.