While we’re all aware that retouching has taken place on basically every advertisement our eyes choose to focus on, we’re rarely given an insight into exactly what trickery is happening.

A former retoucher who’s worked on a number of big brands, including Victoria’s Secret, has spoken anonymously to Refinery 29 to share what really happens on a typical industry bikini shoot, and how what you’re seeing is absolutely not reality.

1.The ‘editing’ begins way before the pictures are taken.

According to “Sarah”, the alteration of how the model looks starts before a camera is even picked up.

“The first thing they do is they put in [hair] extensions. I don’t think I ever was on a shoot with a model that had real hair,” she told Refinery 29.

‘Chicken fillets’ and other shaping pads that alter how the model’s body and breasts look are also used.

“If you hold up the bathing suit in your own hand, it’s so heavy because they have all this shit sewed into it.”

@si_swimsuit on stands now.

A photo posted by Gigi Hadid (@gigihadid) on Feb 16, 2016 at 7:01am PST

2. The cleavage is fake.

Ever asked yourself how the model has cleavage in that strapless bikini top, while you’re struggling just to get it to stay on?

No, it’s not magical anti-gravity spray, but rather a good ol’ fashioned wonderbra – and a lot of brands do it.

Watch: Those Two Girls share the real way to celebrate International No Diet day. Hint: It involves cake. Post continues after video.

“They put a push-up bra under the bathing suit. And we retouch out the bra… a lot of [staffers] would complain because they even did it with strapless stuff,” she said.

“When you’re wearing a strapless bikini, in no way, shape, or form [can] you have cleavage. It’s physically impossible with the way gravity works.”

3. Body hair is edited out.

“They [models] come to these photo shoots and, like, they have their arms up in the classic beach pose, and they have hairy armpits. They all have stubbly pubes — all the normal stuff [non-models have],” Sarah told Refinery29.

4. ‘Skinny’ models are often edited to look curvier.

According to Sarah, retouchers are often told to “add meat to a model’s bones” by making bums bigger, softening sharp joints and hiding any visible ribcage.

“Models are thinner than you actually think they are, and we retouch them to look rounder. We have to curve them out,” she says. (Post continues after gallery.)

5. And ‘plus-size’ models are slimmed down.

We know, it makes no sense.

“Anything to make [them] look delicate. They make the neck more narrow because that is a very female, delicate thing to have.”

6. That body part you’re staring at? It’s probably not real.

Breasts, arms, legs – nothing is safe from being changed.

Sarah says she was often asked to make breasts rounder, higher, perfectly symmetrical and even larger, as most models had A cups.

Sometimes parts are even replaced altogether.

“There’s a lot of the switching bodies up. ‘Can you change these arms with a different girl’s arms, because her arms are making it look like she’s, like, picking her butt’ — or something,” she says.

Image: iStock

7. Colour is also corrected.

There is also retouching that you wouldn't even think about.

Models are often braving the beach in ridiculously cold temperatures, and naturally the human body doesn't exactly respond well to that.

"Everyone has blue hands and blue feet. That’s just the way extremities show up in a picture," she says.

Grey armpits are also a "problem" for brands, as no matter how well you shave, you'll always get a shadow.

Robyn Lawley has launched her own line of swimwear. Image: Instagram/@robynlawley

Image: iStock.

What do you think of photoshopping bodies?