"Girls: wear whatever the hell you want," her tweet read, along with several images in which Petty did just that.
In four separate images, Petty rocks a crop top, bikini, shorts, and leggings.
Using tweets typed by strangers, Petty illustrated why she'd felt it was necessary to flaunt her body online.
"Sorry but if you're over 200 pounds you shouldn't be trying to fit your fat a*s in a crop top. You CANNOT pull it off," read one of the hate-filled messages.
Another added, "Attention all girls over 200 pounds: please do yourself and all of us a favor and throw the booty shorts in the garbage. Gross."
After uploading the post, Petty was shocked to see how much it resonated with other people online. Attracting over 118,000 retweets, it quickly went viral as users from every corner of the globe flooded the comments section of the post to voice their support.
"You look amazing, wear as many bikinis as you can... the world needs to see how beautiful you are," wrote one supporter.
"Yes! You look gorgeous. Girls, women, love yourselves, love your bodies. Believe in yourselves. Don't let anyone else's negativity affect your belief in you," typed another.