Most of us are pretty clued-up on the dangers of smoking when it comes to our health, but did you know that the habit could also play havoc with your looks?

Johnson&Johnson Online Journalism award-winner Rebecca Barnes investigates.

'It may be hard, but the best thing you can do for a beautiful, glowing complexion is to stop smoking. Smoking both dehydrates and deprives your skin of oxygen, so you will see real benefits - skin will become smoother and more radiant.' Sarah Monzani, make-up artist to Madonna

Smoking ages you
Along with sun damage and hard living, nicotine can add years to your appearance. According to Dr. Nicholas Perricone, dermatologist and author of The Perricone Prescription (HarperCollins), the effects of smoking in terms of ageing are significant. When we inhale just one puff of cigarette smoke, more than a trillion free radicals are produced in our lungs, which then trigger an inflammatory response that circulates throughout the body. And if that wasn't enough to persuade you to kick the habit, in 1985 the term 'smoker's face' was added to the medical dictionary. The characteristics of a smoker's face, which tends to make people look older than they are, was defined as the following:

• Lines or wrinkles on the face, particularly radiating at right angles from the upper and lower lips or corners of the eyes, deep lines on the cheeks or numerous shallow lines on the cheeks and lower jaw.
• A subtle gauntness of the features, with prominence of the underlying bony contours.
• A grey skin palour.

Smoking depletes the collagen in your skin
Cigarette smoke contains more than 4000 toxins, many of which are absorbed directly into the bloodstream and are taken by the blood into the skin's structure. Smoking also causes the blood vessels in the top layers of the skin to constrict, so thickening and reducing the oxygen levels in the blood. This also reduces the levels of collagen in the skin.

Smoking thins the skin
'A smoker's skin is normally thinner due to poor circulation, and there are visible signs of premature ageing, with lines and wrinkles more established,' says Laser Aesthetics skin specialist Jane Marsh. In addition, a recent twins study (at St Thomas's hospital) took 25 pairs of identical twins, where one twin was a lifelong smoker and the other had never smoked. Using an ultrasound technique to gauge inner arm skin thickness, some very revealing results surfaced - the smoker's skin was a quarter thinner than that of the non-smoker's, and in a few cases there were differences of up to 40 per cent.

Smoking can alter your body shape
As if maintaining an enviable figure wasn't tough enough already - smoking can create an imbalance in women's hormone levels, which can lead to changes in body shape. You may have heard the saying that smokers tend to be thinner than non-smokers. However, smoking actually affects the endocrinal system - the glands that secrete hormones - and changes body shape, increasing the waist-to-hip ratio. Therefore, despite possibly weighing less, smokers tend to be pot-bellied with spindly legs, probably due to smoking upsetting the hormone levels, thus causing smokers to store the normal amount of fat in an abnormal way, which gives rise to the 'apple' shape.

Struggling to quit? Join the iVillage stop smoking challenge