Hidden cost of thinness

Celebrities may feel they need to be slimmer than ever, but staying super-thin can seriously damage your health. Nicole Kidman was once admired for her porcelain skin and slim figure. Now, it's her stick-like arms and washed-out complexion that provoke comment. Nutritionist Juliette Kellow warns that maintaining a reed-thin physique can pave the way for future illness. Rachel Kaufman investigates.

LOOKS

If food intake is low, it's more likely you will be lacking in vitamins and minerals. 'The body will try to protect itself and direct any nutrients available to vital areas rather than the extremities - the dead tissue such as hair and nails,' explains Juliette. 'So looks start to suffer and you could lose that healthy glow, so highly prized in Hollywood.'

OSTEOPOROSIS

Stars who cut out dairy products are laying themselves open to future bone problems. Calcium and nutrient deficiencies can encourage the bone-thinning disease osteoporosis. 'Until your teens you build up a bone bank from calcium. When you reach your 30s, you stop adding to this and start to live off what you have laid down. So calcium in your diet slows down bone loss,' says Juliette.

'Also, the lighter a person is, the less weight stress there is on the bones - which is a bad thing. A certain amount of stress encourages them to build up and makes them less brittle. That's why it's good to do weight-bearing and aerobic exercises in the gym.'

INFERTILITY

Periods and ovulation may stop in a woman not taking in enough calories. Effectively, the body goes into 'survival' rather than 'reproduction' mode.

Possible low levels of B vitamins, zinc and magnesium due to low food intake affect brain chemistry and hormone function. There may be mood changes and loss of sex drive. Body fat is also linked to the female fertility hormone oestrogen, so if women have a low percentage of body fat and don't produce sufficient oestrogen, this could lead to a risk of infertility.

POOR IMMUNE SYSTEM

The body's immune system can suffer the effects of nutrient deficiencies. You have less ability to fight off colds, flu and bugs, and so become more susceptible to infection. 'Underweight people would need to eat immunity-boosting foods such as red peppers, berries and citrus fruits. They would also need to increase their zinc intake to help fight infection,' says Juliette.

LACK OF ENERGY

Lack of calories can mean lack of energy. The body converts calories into energy and without them simply does not have enough fuel to run on. Just getting through the day can be an ordeal. You could feel tired all the time.

SUPPRESSED METABOLISM

The metabolism slows down because, if you are underweight, your body goes into conservation, starvation mode. It has fewer calories to process and doesn't know when it's going to get more. If the body holds on to calories because of this, and stores fat, you're more likely to put on weight if you later increase your food intake.

CONSTIPATION

If there's not enough food moving round the body, it could lead to a sluggish digestive system, discomfort and bloating. >ANAEMIA

Low levels of iron mean you're not making enough haemoglobin - responsible for red blood cells and transporting oxygen round the body.

'People on a diet are probably more likely to skip foods rich in iron, such as fortified breakfast cereals, red meat, oily fish, leafy green vegetables, nuts and seeds,' says Juliette.

Forty per cent of women under 34 in the UK were shown to be at risk of anaemia due to iron deficiency. Symptoms include tiredness, weakness, dizziness, paleness of skin, brittle nails and headaches. But the deficiency can play a part in leading to chronic illnesses such as cancer, rheumatoid arthritis and other infections.