Dr Fred Kavalier: A Question of Health

I know that I am overweight according to height and weight tables, but I have quite a big frame and am very muscular. I have heard about body-fat analysers, which measure how much fat there is in the tissues. How do these work? Are they any use?

I know that I am overweight according to height and weight tables, but I have quite a big frame and am very muscular. I have heard about body-fat analysers, which measure how much fat there is in the tissues. How do these work? Are they any use?

Medical researchers have been interested in body-fat percentages for a long time, because there is a definite relationship between body fat and diseases related to obesity. Heart disease and diabetes are two good examples ­ the higher your body-fat percentage, the greater your risks. There are several body-fat analysers on the market. They all work on the same principle, called bio-electric impedance analysis (BIA). You either stand on the analyser with bare feet, or hold it in your hands. The machine passes a very weak electric current through the body and the body-fat percentage is calculated by measuring how much resistance there is to the flow of electricity. Fat tends to resist the flow of an electric current more than lean tissue does. If you like electrical gadgets and have some money to spare, a body-fat analyser will tell you something, but I'm afraid I can't vouch for their accuracy. If they encourage you, or anyone who is overweight, to lose a few pounds, then I would say they are useful, but probably not much more useful than ordinary bathroom scales.

An ultrasound scan of my ovaries and uterus has shown several cysts on the ovaries. The possibility of polycystic ovary syndrome was mentioned by the person doing the scan, but my doctor says these cysts are "normal". Who should I believe?

Women with polycystic ovary syndrome (PCOS) usually have a variety of symptoms ­ acne, increased body hair, weight gain and cysts on the ovaries. PCOS can also interfere with the menstrual cycle, causing irregular periods, and sometimes the periods stop completely. Infertility is another part of the syndrome, and this occurs because the ovaries stop releasing eggs. But not everyone who has cysts on the ovaries has PCOS. It is not at all unusual to see a few "normal" ovarian cysts on an ultrasound scan. In fact, cyst formation is part of the natural process of ovulation. If you don't have any of the other symptoms of PCOS, it is likely that your ovarian cysts will disappear spontaneously within a month of two. If you want to find out more about PCOS, have a look at www.pcosupport.org.

Many months ago my left testicle became very tender and appeared to be getting smaller. My GP inspected it and said he could find nothing wrong. He said the reduction in size could be due to hormonal changes. I am prepared to accept this, but can you explain why hormonal changes would affect one testicle only?

A more likely explanation for the pain in your testicle, followed by its reduction in size, is that something has interfered with its blood supply. This could happen after an injury or infection, or the testicle might have got twisted within the scrotum. Hormonal changes would not affect just one testicle. It may be too late to do anything to reverse the damage after all this time, but I would suggest that you ask for an ultrasound scan of your scrotum to try to discover exactly what is going on.

My 82-year-old father has diabetes and takes insulin injections twice a day. Recently he has begun getting "hypos", when his blood sugar drops too low. This causes him to get confused and aggressive. Is there any way he could control his diabetes without insulin?

Your father's blood sugar is dropping too low either because he is taking too much insulin, or because he is not eating properly. Most older people who take insulin for diabetes have started on injections because they could not control it well enough with a combination of a sensible diet and tablets. I therefore think it is unlikely he will be able to manage without insulin, but very likely that he should be taking less insulin, or perhaps a different kind. At his age, the risks in taking too much insulin and causing dangerously low blood sugar are much greater than the risks of his blood sugar running a bit high. You should talk to his doctor, and join Diabetes UK (the new name of the British Diabetic Association) to get information from their Careline. To join e-mail customerservice@diabetes.org.uk, or phone 020-7462 2791

Please send your questions to A Question of Health, 'The Independent', Independent House, 191 Marsh Wall, London E14 9RS; fax 020-7005 2182 or e-mail health@independent.co.uk. Dr Kavalier regrets that he is unable to respond personally to questions