There's far more to reading hands than fortune-tellers' mumbo jumbo - it can be a life-saving skill if you know what to look for.
Place one hand palm down on a table. Now, with the other hand, press the nail of the index finger down. Release, then watch to see how long it takes for the nail's natural colour to return. ‘If it's slow to return, it's a sign of deficiency in iron or another mineral, and you should aim to include more fish, pulses, greens, nuts and seeds in your diet,' says Simon Brown, a macrobiotic consultant for www.chienergy.co.uk. Spoon nails (nails that dip in the middle instead of being convex) are also a sign of anaemia, as lack of iron weakens the nail so it thins and begins to collapse.
How much caffeine we can tolerate varies from person to person. Cold, clammy palms could mean you're having too much. ‘Clamminess is a sign that your body's in a nervous state - and caffeine aggravates that,' says Simon. Hot, sweaty palms are a classic sign of an overactive thyroid, which sends the metabolism into overdrive.
Press your hands together, as if you're praying. Then, keeping your fingers pressed against each other, move the palms away from each other so you flex your hands back from the knuckles. ‘Ideally, you should be very flexible and your hands should form a 90-degree angle. Much less than this suggests your blood vessels are hardening, probably due to overconsumption of salt and saturated fats,' says Simon. ‘Avoid fried foods, red meat, dairy and salt for a month, then try the exercise again.
‘Pins and needles in your fingers is a sign that you're lacking in vitamin B12, which is essential for energy and the nervous system. A deficiency is more likely if you're vegan, as the main sources are meat, fish, eggs and dairy,' says Simon.
Bony lumps on fingers are a sign of osteoarthritis elsewhere in the body - the pea-sized lumps, known as Heberden's nodes, are painful to touch and found around the joints. One study done in the 1970s found that out of 29 patients with previously undiagnosed arthritis of the hip, 18 had Heberden's nodes on their finger joints.
Rheumatoid arthritis sufferers may develop beading on the nails that looks like candle wax dripping down. This is caused by vasculitis, or inflammation of the blood vessels under the nail bed, triggered by the arthritis.
Other lumps and bumps? Knuckles with yellowy fatty lumps that protrude when you clench your fist are a sign of high cholesterol. Knobbly, twisted fingers can also signal sinus problems, according to reflexologists.
‘In Traditional Chinese Medicine, mottled palms point to poor circulation - especially if your fingers often feel cold,' says Simon. ‘The healthy hand is dry, warm and one colour all over.' Very poor circulation due to heart failure can cause nails to turn blue from lack of oxygen. Before an operation you should be asked to remove any nail polish so your oxygen status can be monitored during surgery.
Locate the crease at the base of your little finger, and press the fleshy pad above this with your thumb. A bubble should pop up under the skin on the wrist side of the crease. ‘A small bubble indicates you're well hydrated,' says Simon. ‘No bubble means you're dehydrated and need to drink more, but a big bubble is a sign of fluid retention. Cut down on salt, and assess whether you're drinking too much water - your body has to process it, and may be struggling.'
Reddening palms are a sign of liver damage, as hormonal changes caused by liver disease dilate blood vessels in the skin on the outer palm, a condition called palmar erythema. For reflexologists, who believe our emotional health is reflected in our hands, ‘red hands mean you're fiery - either passionate or angry,' explains Pippa Tucker-Brown of Life and Sole (www.lifeandsole.net). ‘White is a sign that you bottle up your emotions, and yellow is a sign of toxicity, which could be due to a bad diet. Hard skin, especially just below the fingers, suggests you're building a protective barrier.'
Club fingers - fingertips that are dome-shaped, or look like small clubs, are a warning sign of lung cancer, as this anomaly is caused by build-up of a substance called PGE2 that dampens inflammation of the lungs and goes into overdrive if there is a lung tumour.
Oversized hands - hands that become swollen and enlarged may be a sign of acromegaly, caused by a tumour on the pituitary gland that controls production of the growth hormone. Feet, lips, nose and ears can also grow larger.
Two-tone nails - if your nails are pale at the top but brownish towards the tip (known as half-and-half nails), you could have kidney disease. Nail discoloration is thought to be caused by a build-up of urea crystallising under the skin and nails.