Scientists say women's brains are 'wired' to gain weight ... Just blame the hormones!

Sunday, February 07, 2016 by: David Gutierrez, staff writer
Tags: weight loss, women, POMC peptides

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(NaturalNews) Women find it harder to lose weight than men do, because their brains react differently to a family of key metabolic hormones, according to a study conducted by researchers from the University of Aberdeen, the University of Cambridge and the University of Michigan, and published in the journal Molecular Metabolism.

"This study reveals that a sex difference in physical activity, energy expenditure and body weight is driven by a specific source of brain POMC peptides," lead researcher Professor Lora Heisler said.

However, what the study actually looked at was the effect of obesity drugs targeting the activity of those hormones. It did not examine how those hormones – or how men's and women's bodies – reacted to changes in diet and exercise. The real focus of the study is revealed by another statement of Heisler's: "This could have broad implications for medications used to combat obesity, which at present largely ignore the sex of the individual."

What did the study find?

Obesity is now considered a major public health problem worldwide, particularly in wealthier countries.

"More than half of people in the UK are overweight and one in four are clinically obese," Heisler said. "This is an enormous percentage of the population and given the links established between obesity and serious medical illnesses including cancer, heart disease and diabetes, it is essential that we strive to find new methods to tackle this epidemic to improve our health."

For the new study, the researchers used obese mice that had been genetically engineered to lack the ability to produce a peptide called proopiomelanocortin (POMC), which acts as a precursor to a variety of hormones known collectively as POMC peptides.

"POMC neurons therefore make a great target for obesity treatment and are, in fact, an important target of an obesity medication used in the USA today," co-lead researcher Luke Burke said.

Researchers gave the mice the anti-obesity drug lorcaserin, which stimulates the brain to produce POMC peptides. They found that this caused male mice to drop enough mass to be considered a healthy weight again. While female mice also lost weight, they remained obese.

The researchers found that lorcaserin did increase POMC peptide activity in both males in females. In males, this had the expected result: the mice ate less, became more active, and burned more calories through heat (metabolism). In females, however, the only effect was decreased appetite.

"In female mice, this source of POMC peptides does not strongly modulate physical activity or energy expenditure," Heisler said. "So, while medications targeting this source of POMC peptides may effectively reduce appetite in females, our evidence suggests that they will not tap into the signals in our brain that modulate physical activity and energy expenditure."

What the study did NOT find

In spite of how this study is being reported on in the media, it did not actually prove that it is harder for women to lose weight than for men, or that women's brains are wired to keep pounds on.

First of all, the study was conducted in an animal model, and thus its findings cannot be definitively applied to human beings.

Perhaps more importantly, the study only looked at one very specific question: the difference in the way that a particular anti-obesity drugs affected the brains, metabolism, activity and weight of male vs. female mice. The study says nothing about how changes in diet or exercise affect men or women differently, or even male or female mice. Notably, the female mice exercised less than the male mice, and also lost less weight.

In addition, no changes were made to the contents of the diets of either male or female mice. Instead, the mice were simply given a drug that changed their appetites.

Sources for this article include:

Telegraph.co.uk

MedicalNewsToday.com