Move over festive boozing and overindulgence. January’s here - and detoxing is the flavour of the month.

With far more booze and sugar on the menu than usual, and feasts that require belt removal and a lie-down afterwards, no wonder many of us are feeling monumentally sluggish and bloated come January.

Detoxing may seem like a recent celeb-fuelled phenomenon, or just a fancy word for dieting, but that’s not really the case.

Celebrities have no doubt helped make the detox more mainstream but many of the principles and methods can be traced back thousands of years, for instance in Ayurvedic Indian and Chinese medicine.

The Ancient Egyptians were fans of colonic irrigation (the ultimate internal cleanse!), and fasting has been around since the dawn of time, for both religious and health reasons.

While weight loss is often cited as a key motivation, and indeed one of the rewards, detox devotees will tell you the benefits are far wider.

As the name suggests, the basic principle is to eliminate toxins - chemicals absorbed through food and drink, cosmetic and cleaning products, the atmosphere around us - from the body.

Methods of achieving this range from more extreme (like 10-day liquid-only fasts) to moderate three or seven-day plans, with specific food types (such as refined sugars, dairy and junk foods), alcohol and caffeine banned.

And while elimination is often the focus, adding more “good stuff” to the system features in many plans too, such as juicing, where nutrient-packed juices replace meals.

As well as feeling and looking physically better and healthier, fans say they feel mentally re-charged after a detox too.

“The key principles for me are to clean the system,” says Fiona Robertson, 48, who runs detox holidays at Retreat Biarritz (www.retreat-biarritz.com). “Firstly by returning to a simple cleansing diet, introducing more vegetables and fruits in the way of juices.

“Secondly to clean the digestive system and re-set your body’s way to eliminate old waste and toxins from you on a cellular level.

“Once you eliminate toxins and old waste successfully, your skin will glow and your eyes will sparkle; your insides are the barometer for what you see and how you feel on the outside.”

Robertson’s first encounter with detoxing was during a trip to Thailand in 2003, in search of an experience she’d “never get at home”.

“I walked into a bar and saw a leaflet proposing a detox experience and I thought, ‘I must try that - I’ll never do that again’. How wrong I was!

“I experienced a lift in energy, a clear mind, became really focused. I made some major decisions in my life that were to bring me to where I am today, running a business helping people detox, helping them gain more energy than they’ve ever experienced before.”

James Griffiths, founder of Wild Training (www.wildtraining.co.uk), a fitness franchise which also runs retreats incorporating exercise, detox and relaxation, is another advocate.

“The first week [of our food plan] is what we call our elimination plan,” explains Griffiths, 26. “It removes all the bad stuff from people’s diets that slow their metabolisms down, makes them store fat and reduces energy levels.

“Detoxing does work but there are healthy ways to reduce the level of toxins in your body and other more dangerous strategies,” he adds. “Your liver deals with a lot of toxins and can swell up to four times its normal size if we consume the wrong nutrition. Once your liver can’t take anymore, your body starts storing toxins you can’t process in your bum, thighs and, most often, abdominal area. There is a reason it’s called a beer belly!

“If you reduce or cut out alcohol, caffeine and refined sugars, you might feel heavy for a day or two, depending on how bad you normally are, but before long you will feel awesome. Clear head, better sleeps, more energy, clearer skin and eyes.”

As leading dietician Dr Carrie Ruxton from the Tea Advisory Panel (TAP; www.teaadvisorypanel.com) says: “Following a detox plan can be more straightforward than people think, it does not need to be extreme.

“It is important to make sure you are getting the right nutrients and antioxidants with your food combinations.

“Many of us won’t necessarily be aware how beneficial some food and drinks can be, for example, our favourite British cup of black tea is a good source of natural antioxidants to help support heart health, weight control, and brain health.”

For lots of people, in January especially, reducing alcohol intake is another big appeal of the detox, which in itself can be a great health boost - both inside and out.

Dr Sarah Jarvis, medical adviser for Drinkaware (www.drinkaware.co.uk), says: “Depending on how much you’re drinking, you may notice numerous benefits from stopping even for a short time. You’re likely to sleep better and feel more rested when you wake up; you may have more energy; your skin will look less sallow and tired.

“It also won’t take long for you to lose weight - a large glass of wine has almost 200 calories, and a new report by the World Cancer Research Fund suggests that about 10 per cent of average calorie intake among people who drink comes from alcohol.”

Dr Jarvis warns that people shouldn’t be fooled into thinking that a short-term detox “undoes” the damage of longer-term bad habits.

“One of the problems of ‘detoxing’ from alcohol is that many people believe that if they stop drinking for a month, it cancels out any ill effects from drinking over the recommended limits for the other 11 months a year. That’s simply not how it works,” she says. “If you’re drinking within recommended limits, your liver is ‘detoxing’ - filtering the toxins in alcohol from your body - all the time, and you don’t need to stop for a month.”