The star, 30, posed in just her underwear before telling her 1.5million followers to only swipe right if they are not "faint hearted".
The second photo shows a huge scar the Love Island beauty received from the surgery while she warned her fans about the unknown "repercussions" of the procedure.
Laura wrote: "Recently I decided to undergo a breast reduction. I had my first breast augmentation at 18 (12 years ago) After this length of time its normal to consider a replacement. I just want to make clear that even though at 18 years old I was very mature for my age (more mentally) I really had no idea who I was or what I was doing to my body.
"Here’s what they don’t tell you, every surgery has repercussions years down the line so this quick fix mentality which we all suffer from from time to time will most definitely come back to bite you in the ass.
"It's not like buying a pair of jeans that don’t fit so you just take them back. Theres no refunds when it comes to interfering with our bodies.
"Being completely honest, after seeing myself on TV I realised that my chest looked way too big for my frame and after many shooting pains in my left boob I knew it was time for a change.
"My original implants were so large that over time I’ve actually stretched my skin and breast pocket so much that I was told my choices would now be limited. This is just something I would never have thought about all those years ago.
"If I could have it my way, I’d go back and never have my first surgery at all. Having no implants and to be natural is honestly the person I feel inside. I just want to say to young girls or guys out there that think surgery is the answer to all their problems, just know the decision to go under the knife is huge and really has its consequences.
"My message to you is yes, fashion changes, but our bodies don’t need to!"
Earlier this year Laura was forced to hit back at body-shamers who claimed she was "too skinny" when she posted a bikini photo.
One troll wrote: "Oh no u look really thin hunny.not very healthy hunny. but ur lovely person"
Another added: "Looking frighteningly skinny but very beautiful x"
However, she pre-empted the criticism by writing: "Before anyone starts on my leg I'm just hypermobile so I dunno why my limbs move abnormally right."
Former air hostess Laura was a favourite on Love Island 2018.
She finished as a runner-up with Paul Knops before dating Max Morely on-and-off from October 2018. The pair are currently separated.