I love this article that I read at mirror.co.uk. This is part of it. It says that just by looking in the mirror you can tell if there is something internally wrong with you. I find it really useful. I now learned that I should get my cholesterol checed!

Red, sore tongue
Sometimes this can indicate anaemia, common in women of childbearing age, so see your doctor for a blood test and increase your intake of iron-rich foods. It can also be a sign of vitamin deficiency, so make sure you’re eating your five portions a day of fruit and veg.
White coating on tongue
Smoking can cause a grey-white build-up. In babies or those with lowered immune systems, patches with red, sore areas underneath are a sign of thrush. Patches which can’t be scraped off with a tissue should be investigated by your GP urgently - they can be thrush or a pre-cancerous warning sign.
Mouth ulcers
We all get the occasional ulcer, normally caused by a minor trauma to the tongue or gums. Avoid hot, spicy or acidic foods and try rinsing your mouth with a salt-water solution. Recurrent painful sores can occasionally be a symptom of a serious bowel condition like Crohn’s disease or colitis, so see your GP for tests.
Cracks at the corners of your mouth
Can be a sign you’re deficient in B vitamins. Increase your intake of meat, whole grains and dark green veg, or try a B vitamin complex.
Sores on lips
If it’s painful it’s most likely to be a cold sore. These are caused by the herpes virus, which most of us pick up in childhood - in some people, repeated outbreaks are caused by stress or lowered immunity, so try exercise to cut tension, and have plenty of fruit, veg, fish and whole grains in your diet. A persistent, painless sore on or inside your lips, or elsewhere in your mouth, can be a sign of oral cancer, especially if you smoke and drink heavily - see your doctor.
SKIN
Spots
They could signal an underlying hormonal imbalance. “One study found 80 per cent of women referred to dermatologists with acne have polycystic ovary syndrome (PCOS),” says Colette Harris, author of The PCOS Protection Plan (Hay House, £12.99). “The condition makes the skin’s oil glands more sensitive to the hormone testosterone, triggering excess oil, which can lead to spots.” See your GP, who may suggest antibiotics, or the Pill to balance hormones. Spots can also be a sign of stress which can interfere with hormones. Try exercising to keep calm. Some studies have suggested foods with a high glycaemic index could contribute, so try reducing sugar and white bread, and switch to alternatives such as fruit, wholegrain bread and wholemeal pasta.
Flaky patches
Dry, reddish scales around the hairline, the nose and in the eyebrows are typical signs of seborrheic dermatitis, an inflammatory condition. Although it feels and looks dry, it’s more common in oily skins. Seborrheic dermatitis can just be hereditary, with no other apparent cause but stress and excess alcohol can aggravate it, so take steps to address both.
Yellowish skin
Most commonly a sign of jaundice, which can develop as a result of liver disease, or blockages in the bile ducts or gall bladder. See your doctor.
EYES
White ring around the iris
A pale ring around the coloured part of your eye may be a symptom of raised cholesterol, according to the British Heart Foundation (www.bhf.org.uk). Book a cholesterol test with your GP, or try the SELFCheck Cholesterol Level Test, £9.99 from chemists. Regular exercise and a diet low in saturated fats can help bring down cholesterol.
Puffy eyelids
Can be caused by an allergic reaction to make-up, so try switching to a hypoallergenic brand such as Almay. Other allergies, such as hay fever and eczema, can also be a cause, and eye infections such as conjunctivitis can cause your eyelids to swell. Your pharmacist can give you eye-drops for allergic reactions and infections, and try putting cold camomile tea bags on your eyes for 10 minutes. More rarely, puffy eyelids can be a sign of an underactive thyroid, so if they’re a long-term problem, see your GP to rule out underlying medical causes.
Pale lower lids
If the skin inside your lower eyelid looks pale pink rather than bright red, it could be a sign of anaemia, a lack of haemoglobin in your blood. Ask your GP for a test and eat more iron-rich foods such as red meat and green veg.
Yellow bumps
Small, yellowish lumps above and below your eyes are deposits of fat and could signal high levels of unhealthy LDL cholesterol. See your pharmacist or GP for a cholesterol check.