Why fat can be good for you

An astonishing new picture of Wonderbra model Eva Herzigova shows how a desire to shed a few pounds has transformed her once-voluptuous figure. But while she may look thinner, she looks far less healthy, which is the conundrum most of us share - thinner or fuller, which is really a healthier shape for you?

Most people think they should lose some weight, but it's not as simple as watching the scales. To get an accurate predictor of your health, you should be looking at just how much fat you have on your body.

Too little, like Eva, can be as damaging as too much. A recent report identified a low body-fat ratio as a prime cause of infertility, as well as other health problems. And women need to have about 25 per cent body fat to be able to conceive.

We tested three young women, each of whom weighs the right amount for their height, to find out whether they should be paying less attention to the scales and more to their lifestyle.

We used a monitor which measures body fat using very low electrical currents. While the charge passes easily through muscle tissue, it encounters resistance when going through fat. When the reading is set against gender, height and weight, it computes the body-fat percentage. The healthy range for women aged between 20 and 39 should be between 21 per cent and 33 per cent.

We showed the results to fitness expert and nutritionist Jane Wake, owner of Body A-Wake Personal Training.

Too little fat

Weight: 9st 5lb. Height: 5ft 8in. Body fat: 18.5 per cent.

Esther Gillies, 24, is a receptionist, who lives in Tottenham. Although not underweight, her body-fat ratio is too low to be deemed healthy, which may lead to problems in later life. She exercises at least four times a week and eats a very low-fat diet.

Jane Wake says: "Esther's body fat is lower than what is considered to be a healthy range and I would be concerned if she allowed it to drop lower. Some women can get obsessed with body fat, to the extent that they cut fat out of their diet altogether and exercise to excessive levels. This can upset their nutritional balance, making them more susceptible to injury and illness. In extreme cases this can lead to malnutrition, their periods stopping and a high risk of developing osteoporosis. A certain level of body fat is essential, not only for health but for life. Esther should keep a check on her body fat once a month to ensure it doesn't drop any lower. It would also be useful to keep a check on hydration levels by drinking plenty of water every day."

Esther says: "I think that the reason my body-fat ratio is low is because of the amount of exercise I do. I go to the gym four times a week and do Body Combat and Pilates classes, work out with a personal trainer and do plenty of cardiovascular work such as treadmill, exercise bikes, rowing machine and step. I eat very healthily: loads of pasta, vegetables and rice. I always choose wholemeal carbohydrates and avoid fatty foods, although I have the very occasional binge on chips. I used to think I was underweight, but actually I don't worry about my weight at all now. I feel healthy, eat and exercise well, so I'm perfectly happy."

The right fat

Weight: 9st 10lb. Height: 5ft 8in. Body fat: 24 per cent.

Gemma Cavill, 22, from Cheshunt, Herts, works in the sports department at John Lewis, Oxford Street. She goes to the gym twice a week and takes a weekly yoga class. She eats a healthy diet, rich in fruit and vegetables. Her body fat falls in the middle of the healthy range.

Jane Wake says: "Gemma has a great attitude, both to diet
and exercise, and her body-fat level is proof of how exercise and healthy eating can put you in optimum health. One thing, though; she should keep the crisps to occasional snacks and not make them a habit.

Her measurements also demonstrate how important body fat is compared with just weight readings. If you were to compare the weight of many very slim women of the same height as Gemma, you often find their weight is lower yet their body fat is higher. While young, this may not concern some women, but as they get older they may find their body fat levels increasing further, putting them at a greater risk of disease. With a high level of lean muscle mass you can maintain a healthy metabolism and are more likely to keep within this healthy range. Be careful to maintain your exercise and healthy-eating programme - regularity is the key - and make your current habits stick for life.î

Gemma says: "I eat a lot of salad and pasta with tomato - I very rarely have creamy sauces. I seldom eat fatty foods and very rarely red meat. I like to include plenty of vegetables and fruit in my diet but occasionally have a tendency to snack on crisps if I'm really hungry between meals. I go to the gym at least twice a week, more if possible, and I do a weekly yoga class. I think I get a good amount of exercise at work as I'm on my feet all day, so I'm sure I must be burning fat reasonably well. I know that I'm in the normal range of body fat for my age, so I can't see that there's anything to worry about."

Too much fat

Weight: 10st. Height 5ft 4in. Body fat: 34 per cent.

Nicky Ball is a 21-year-old fitness instructor who lives in Battersea. She works out three times a week doing weights and cardiovascular exercise, and has done for several years. Despite this, her body-fat ratio is slightly more than recommended for her age group (up to 33 per cent), which increases her risk of acquiring serious health problems as she gets older. She admits her habit of snacking and eating high-fat takeaway foods are to blame.

Jane Wake says: "Nicky is over the healthy body-fat range and has to address the quality of her food intake. If she doesn't, her fat levels will gradually increase and so increase her risk of coronary heart disease, high blood pressure and diabetes.

"However, I would also be concerned that Nicky doesn't go overboard in changing her diet, as this can often lead to eating disorders and make someone who relies on being fit for their job more susceptible to illness and injury. She should think about eating to maximise her energy levels. This means avoiding refined, processed foods which are quick to satisfy but often leave you feeling low. She should go for plenty of fresh vegetables, lean meats, fish, pulses and whole grains, which are full of antioxidants to boost the immune system and lower the risk of illness."

Nicky says: "I think my high body-fat ratio is definitely due to my bad diet, which I haven't managed to sort out since my student days. Now, I work shifts, and tend to have microwave meals, takeaways like McDonald's and pizzas when I'm really tired after a late shift. When I look for convenience foods I buy whatever I fancy and that doesn't usually mean low-fat foods. I also have a tendency to snack on crisps. I do make healthy meals occasionally: lots of vegetables and chicken, I avoid red meat. But I am determined to try to bring down my body-fat ratio because I know that, being in the fitness industry, I should practise what I preach."

Tanita Body-Fat Monitors cost from £40 to £129.99. Available from Argos, Boots and John Lewis. Body-A-Wake Personal Training: 020 8674 2042.