Roxy Jacenko has shared her clothing size after shedding a whopping 18 kilograms.

The PR mogul, 45, posted to Instagram Stories on Monday to show off her trim figure in skin tight activewear. 

Alongside the image in which she posed in the revealing black ensemble, Roxy wrote: 'I'm in an XS'. 

An XS, otherwise known as an extra small, typically corresponds to a size 8 in Australian sizing.  

In her selfie, Roxy flaunted her incredible figure as she posed for a mirror selfie in her dressing room.

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Roxy could be seen wearing a tight black one-piece by activewear brand Cleo Harper that boasted thigh-length shorts and a zip front.

The Aussie socialite poured out of the romper, which accentuated her perky cleavage, tiny waist and long trim pins.

She paired the laidback ensemble with $1,908 Nike Air Presto Off-White running shoes.

Roxy wore her hair in loose waves across her shoulders while opting for an all-natural makeup look.

In the background of the shot, eagle-eyed fans could spot Roxy's Christian Dior tote bag, which retails for a whopping $4,715.

Roxy has admitted to trying Ozempic in the past to lose weight but suffered a terrifying overdose.

But now she swears by a new supplement called Eimele which she has called a 'natural Ozempic'.

She recently gave an insight into her daily ritual and 18 kilo weight loss.

According to the website, Eimele provides 'plant-powered solutions' for a variety of concerns, including weight management.

The brand's Calibrate Reds Max is said to help 'limit sugar and carb absorption' while simultaneously 'reducing fat storage'.

The powder sachets are designed to be taken dissolved in water at the start or during the biggest meal of the day.

Roxy recently revealed the extreme measures she goes to in order to maintain her goal weight of just 50.9kg.

She told Daily Mail Australia she is doing daily contrast therapy, which involves taking baths in warm and cold water from Monday to Friday.

This method is believed to help to improve blood circulation throughout your body.

She also does 40 minutes in an infra-red sauna each day before completing a 45-minute workout on the treadmill at speed 6 and rolling hills, as well as low-weight exercises.

'I don't do breakfast or lunch, instead I do dinner at 7pm each day which is focused on protein only and salad,' she explained.

Roxy also revealed she eats just one meal a day at dinner which is focused on protein only.

'Last night I had grilled calamari, rocket, pear and Parmesan salad. If I'm desperate for something sweet, I have dark chocolate-covered sultanas.'