Sitting at a desk all day isn't doing your behind any favours.

In fact, recent studies have suggested that sitting for long periods can make your bottom flat and saggy as the muscles start to waste away from lack of use and fat cells can multiply.

Dubbed 'desk derriere', it's fast becoming a frightening reality for many 9-5 office workers all over the country.

Luckily, there are ways to avoid this. Mario Kaspers - who has trained with the likes of Courtney Cox, as well as Made in Chelsea stars Lauren Hutton and Rosie Fortescue - shares his top tips for keeping your posterior pert.

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1. TAKE A BREAK

This may seem like an obvious one but if you're desk-bound for most of the day, make sure you take regular breaks.

This will keep your blood flow moving and keep your muscles active.

"If you're sitting behind a desk for hours on end, this can cause the muscles in your bottom to lose their tone and shape," warns Kaspers.

"Try and get up from your desk every 30 minutes and take a walk. Not only will this help to increase blood flow, it will give your eyes a break from your computer screen and clear your head."

2. EMS TRAINING

Electrical Muscle Stimulation (EMS) training can help to offset the lack of blood flow to the glutes, by stimulating your muscles and increasing the blood circulation and flow to this area.

It involves wearing a bodysuit which delivers impulse currents to reach deep muscle layers.

"Specific body parts can be targeted like the glutes, where up to 98 per cent of muscles can be worked compared to 50 per cent in conventional training," says Kaspers.

3. DRY SKIN BRUSHING

This ancient beauty and health practice is gaining modern popularity, and is now even offered at spa resorts.

"Try this in the morning before your shower with a firm, natural bristle brush to increase circulation and energy," says Kaspers.

"Dry skin brushing can also help with cellulite, as many have found it makes their skin softer and smooths away any imperfections."

4. MEDICINE BALL

Medicine balls can work wonders to strengthen and re-activate your muscles; bring one to the office for a quick desk workout.

"Try lying flat on your back and placing both heels on top of the medicine ball, then push your heels down through the medicine ball and raise your hips to a bridge position," says Kaspers.

"Lower your hips back down to the starting position and repeat and complete as much as you can to help firm up those glutes."

5. EAT OILY FISH

"It is important to incorporate the right types of fats in your diet for optimum health and wellbeing," says Kaspers.

"By eating a diet rich in oily fish, you can improve skin elasticity all over your body, including your bottom."

He suggests eating two portions of oily fish a week such as salmon or tuna, to enhance the cellular function and improve the overall appearance of the skin.

Omega-3 fats in fish oil can also improve the texture and tone of the skin by making it smoother and more hydrated.

Desk derriere: The facts

Scientists have confirmed that sitting around really does cause a fat backside.

The more we sit down, the more fat cells in the buttocks expand creating a rounder derriere.

An Israeli study from 2014 revealed that 'cellular expansion' plays a key role in fat production because the pressure on cells causes them to increase in size by 50 per cent.

The study, published in the Biophysical Journal, revealed that fat cells change in structure under pressure and are likely to expand, leading to weight gain.

"When they gain mass and change their composition, expanding cells deform neighboring cells, forcing them to differentiate and expand," said Professor Gefen.

"This proves that you're not just what you eat. You're also what you feel - and what you're feeling is the pressure of increased weight and the sustained loading in the tissues of the buttocks of the couch potato."