Eyebrows that are thinning at the outer corners are a common sign of an underactive thyroid, which can cause weight gain! If you are noticing sparse or balding eyebrows, ask your doctor for a thyroid function test. “If eyebrows start to look unusually wiry or long, however, that could be a sign the adrenal glands that produce stress hormones are under pressure,” says nutritional medicine expert Fiona Tuck. So, if you notice your eyebrows growing bushlike, it’s time to reduce your stress levels.

There’s a perfect length for your eyelashes and that’s about a third of the width of your eye. Eyelashes form a barrier to control airflow and the rate of evaporation from the surface of the cornea. But while shorter lashes decrease this protection, slightly long lashes cause the biggest problems as they funnel dust into the eyes and increase the airflow around the area, increasing risk of dryness and irritation. If you’re always rubbing your eyes, skip mascara, false lashes or extensions and see if it helps.

(Read more: 5 Bad Habits That Cause Eyelashes To Drop)

There are clear signs associated with overeating or intolerances to certain foods that show up on the face. Here’s what to look out for:

Too much gluten: Spots on the forehead, puffy cheeks and jowls that make your face look bloated, redness or red spots on the cheeks and spots or darkened patches on the chin.

Too much dairy: Swollen eyelids, undereye bags, darkness under the eyes, widespread spots and pale cheeks.

Too much alcohol: Pronounced lines or spots between the brows, droopy eyelids, feathery lines on the cheeks, reddish skin and enlarged pores.

Too much sugar: Lines and wrinkles on the upper forehead, sagging under the eyes, spots (especially inflamed ones), and a greyish hue to the skin.

When we breathe in through the mouth two things can happen to the particles we inhale – they can enter our system or bounce off our lips. The larger your lips the more particles that bounce back into the atmosphere. If you’re not blessed with a plump pout, there’s another simple way to reduce your cold risk: just use lip gloss. Lip gloss causes particles to stick to the lips and prevents them from entering the system.

(Read more: Super Hydrating Lip Plumpers That Will Give You A Fuller Pout)

A red tip at the end of the nose indicates an excess of fire chi, which is linked to high levels of stress or anxiety and a tendency to have high blood pressure. If you regularly suffer from stress and a red nose, get your blood pressure checked. As well as trying to reduce stress, aim to minimise sugar, spices, coffee, alcohol and fried foods and introduce more wholegrains, vegetables and pulses to help balance the excess fire chi.

The more crowded or crooked your teeth the harder they are to clean correctly, which increases the risk of plaque and tartar build-up that can lead to gum inflammation (gingivitis) or periodontal disease. If you have very crowded teeth, your dentist or hygienist should be able to spot any areas you’re not cleaning correctly and give you tips on how to change things like interdental brushes instead of floss, or brushing hard-to-reach areas of your mouth at an angle.

(Read more: Foods To Eat For Naturally Whiter Teeth)

Poke your tongue out in the mirror and allow it to relax fully. If it shakes or quivers as you do this, your magnesium levels could be low. A major role of magnesium is to relax the muscles in your body, and because the tongue is a muscle, a deficiency in magnesium can prevent the muscle fibres from fully relaxing, which leads to it quivering. Correcting this is relatively simple – just eat more magnesium-rich foods like almonds, cashews, legumes and leafy green vegetables.

While a little hair above the upper lip is normal, hair or acne that appears around the jawline can be a sign of PCOS (polycystic ovarian syndrome). This is due to elevated androgens, which are male hormones like testosterone, in the body. This causes women to develop hair growth in masculine areas of the face and increases sebum in the skin, leading to acne. If you suspect your facial hair issues might be PCOS-related, see your doctor for advice.

(Read more: Simple Tips For Flawless Brows From A Beauty Expert)

The more impulsive we are the more we’re at risk of overeating, drinking too much alcohol and taking risks like speeding – and lines in your eyes indicate impulsiveness. Your eyes, or specifically, structures called contraction furrows that appear in the iris, can reveal someone’s tendency to be impulsive. These furrows appear as light circles of pigment around the iris, and the more you have, the more impulsive you are likely to be, say Swedish researchers.

How wrinkled do you look compared to your friends of the same age? If it’s more so, then you might need to take extra care of your bones. US researchers found that the more pronounced a woman’s wrinkles were by early menopause, the lower her bone density. The reason is that skin and bone share common building blocks in collagen. As we age, the changes in collagen that cause wrinkles are likely paralleled by similar changes that affect bone.

(Read more: 10 Foods That Could Prevent Wrinkles)

(Text by Helen Foster, Good Health (Bauer) / Additional Reporting by Natalya Molok)