As our knowledge continues to grow so too do what at first sight appear to ludicrous claims and this one certainly seems to fall into this category. Can anyone honestly believe that the soap we use in the bath, or the shampoo, can actually be adding to the growing problem of obesity? Well, the answer appears to be that it just might be.

One thing we do know is that the body is a complex chemical factory and that good health is largely a result of keeping the chemicals in the body in the correct balance. If we introduce chemicals into our system that balance can quickly be upset and our health can suffer in a variety of different ways. We also know that there are many ways in which chemicals can enter the body, including through our skin which is of course porous. Against this background it would seem quite feasible that chemicals contained in soap could indeed enter the body. So just what are these chemicals and why might they be a problem.

The chemicals in question are known as phthalates and appear in thousands of household products including children's toys, detergents, food packaging, pharmaceuticals and personal care products, such as nail polish, hair sprays, soaps, and shampoos.

These chemicals have been under investigation for some time now and, although the connection is not yet fully understood, it is widely believed that phthalates play a part in producing low sperm counts and low testosterone levels in men. It is also known that men with low testosterone levels are also prone to insulin resistance and to abdominal obesity. The initial conclusion therefore might be that phthalates produce abdominal obesity in men indirectly by lowering testosterone levels.

Now at this stage there is not a great deal of evidence to support this theory, apart from a few studies such as one which showed that men with high levels of phthalates in their urine did indeed display higher than average levels of body fat, and further studies need to be carried out to see whether or not this is actually the case.

So ladies, you appear to be in the clear. Or are you?

As with most things in life this is likely to turn out to be a very complex multi-factor problem with the link between phthalates, testosterone and abdominal obesity being just one facet. As research continues it is highly likely that phthalates will be found to produce a whole host of other reactions including almost certainly an effect upon the thyroid gland which could also cause obesity, this time in both men and women.

Before you stop washing though and spark another epidemic, remember that it is very early days in this investigation and, even if the connection is proved, it is unlikely that phthalates will account for anything other than a tiny part of the obesity equation.