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Scientists propose novel explanation of obesity

Posted June 12, 2014
Picture: Portrait of a Gentleman. Author: Charles Mellin. Year: 1630. Source: Wikimedia Commons

Picture: Portrait of a Gentleman. Author: Charles Mellin. Year: 1630. Source: Wikimedia Commons

Obesity is among the biggest health-problems of our century. However, presently available explanations cannot account for the fact that there exists a vast array of different reactions to different diets and lifestyles. Two medical scientists at the University of Adelaide propose a novel hypothesis which can enormously help in the fight with this global problem.

Pandemics of obesity is one of the most challenging issues presently. “It is currently estimated that 1.4 billion individuals are overweight and 500 million people are obese globally, many of them in developing nations,” the researchers say. Usually fatness is explained via a mechanism of positive energy balance. A positive energy balance is a consequence of energy intake being higher than what is consumed in external work and other bodily means of energy expenditure.

James P. Grantham and Maciej Henneberg raised an alternative hypothesis. They conjecture that overweight is strongly dependent on the physiological and anatomical differences. During their study conducted with the respondents from South Africa, scholars found evidence which suggests: “hormonally driven weight gain occurs more significantly in females than males.” Moreover, the available data reveal that interesting differences between well-developed and less-developed countries exist. “Average prevalence of obesity in males differs highly significantly between rich and poor countries whereas there is no significant difference between those countries in the average prevalence of female obesity,” the researchers note.

But why overweight rate among females is so consistent across the globe? The scientists think that this difference is caused by a particular hormone – oestrogen. “Amongst women, oestrogen exposure is known to cause weight gain,” they claim and argue that such way to get body weight was an evolutionary advantage, because food resources were often scarce.

However, situation has changed drastically in some parts of the world. A lot of societies live in the age of affluence. “The mechanism of adipose preservation through oestrogen is ultimately unnecessary in such an environment and may, in fact, become deleterious,” the scholars say. But why does the weight of males differs considerably in poor and rich countries?

Grantham and Henneberg propose number of interesting explanations in their article. For instance, it is well established that soy products contribute to body weight significantly. Interestingly, soy products are popular in wealthly countries, such as the U.S., and are rich of oestrogen. “Perhaps, in societies with particularly high dietary saturation of soy, this works to ‘feminise’ the males?” the scientists suggest.

Article: Grantham J.P., Henneberg M., 2014, The Estrogen Hypothesis of Obesity. PLoS ONE 9(6): e99776. doi:10.1371/journal.pone.0099776, source link.

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