Female Hormones Play a Key Role in Obesity Among Western Men

A team of Australian researchers found that an imbalance in female sex hormone among men is a key factor for the rising obesity rate.

The new research, led by University of Adelaide, highlights the association between obesity among western men and exposure to substances containing female sex hormone estrogen. This hormone is generally found in soy products and plastics.

The study led by medical student James Grantham and co-authored by Professor Maciej Henneberg, Wood Jones Professor of Anthropological and Comparative Anatomy, found that unlike the developing world where women generally have greater levels of obesity than men, it was very different in the developed world.

"Hormonally driven weight gain occurs more significantly in females than in males, and this is very clear when we look at the rates of obesity in the developing world," Mr Grantham says. "However, in the Western world, such as in the United States, Europe and Australia, the rates of obesity between men and women are much closer. In some Western nations, male obesity is greater than female obesity. While poor diet is no doubt to blame, we believe there is more to it than simply a high caloric intake."

According to Professor Henneberg, exposure to estrogen is known to trigger excessive weight gain mainly through thyroid inhibition and variation of the hypothalamus. 

In the United Sates there is a high dietary saturation of soy and this could be feminizing the males as soy contains xenoestrogens.  Men in these communities might be artificially mimic the female pattern of weight gain.

Another well-known source of xenoestrogen is polyvinyl chloride (PVC) that is widely used in wealthy countries.  PVC is commonly found in plastic and other household products.

The researchers, however, claim that certain micro-evolutionary changes taking place within the western societies is triggering the changes in testosterone as well estrogen in men. This would help explain the drop in sperm count among men in developed nations.

However, further research is needed to understand whether or not the environmental factors are triggering 'feminization' of men in the western World.

The study was documented in the journal PLOS One.