PFASs - the hidden chemicals in drinking water and foodstuffs that make the world fat
Fat-proof packaging of not so healthy foods such as pizzas and fries, dirt-resistant clothing and non-stick coatings of pans all contain perfluoroalkyl substances [PFASs]. Animal studies suggest that these PFASs, after entering the body through drinking water or junk food, diminish the potential to break down fat reserves. In PLoS Medicine American researchers have published the first human study that confirms this dark suspicion.
About fifteen years ago, 621 Americans participated in the Pounds Lost trial, in which they first went on a weight-loss diet for half a year, and then tried to stay maintain their new weight for a year and a half. Before the experiment started, researchers at the University of Harvard determined the concentration of PFASs in their blood.
One type of PFASs that researchers often find in the blood of humans is perfluorooctanoic acid [PFOA]. In this post we will limit ourselves to PFOA.
The more PFOA there was in the subjects' blood, the less weight they lost in the first six months of the trial - and the larger the regain.
During the trial the researchers also determined the participants' resting metabolic rate [RMR]. That's the amount of energy the subjects used at rest. The RMR decreased during the weight loss phase, but during the weight maintenance phase it increased again. At least: in the subjects with relatively little PFOA in their blood. In the subjects with a lot of PFOA in the blood, the RMR remained low.
"PFASs have been linked with excess weight gain and obesity in animal models, but human data has been sparse", tells research leader and nutritional scientist Qi Sun, who is affiliated with with Harvard Medical School, in a press release. [harvard.edu February 13, 2018]
"Now, for the first time, our findings have revealed a novel pathway through which PFASs might interfere with human body weight regulation and thus contribute to the obesity epidemic."
"We typically think about PFASs in terms of rare health problems like cancer, but it appears they are also playing a role in obesity, a major health problem facing millions around the globe", adds co-author and environmental scientist Philippe Grandjean, who is affiliated with Harvard Chan School. "The findings suggest that avoiding or reducing PFAS exposure may help people maintain a stable body weight after they successfully lose some weight, especially for women."
Because the packaging materials of junk food contain PFASs, people who eat a lot of junk probably have more PFASs in their blood than people with a healthier lifestyle. These people probably consume more bad carbohydrates and fats, may move less, and also have less lean body mass.
Perhaps we should wait for studies that distinguish between those lifestyle effects from the biologicals effects of PFASs before we blame the obesity epidemic on substances in the drinking water.
PLoS Med. 2018 Feb 13;15(2):e1002502.
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