A new study shows that perfluoroalkyl substances (PFAS) can contribute to a slow metabolism. PFAS, which include PFOS and PFOA, are commonly found in fast food wrappers and nonstick cookware surfaces, due to their water- and oil-repellant properties.
The study, which was performed by researchers at Harvard’s School of Public Health and published in PLOS Medicine, points to these substances hindering durable weight loss; lead researcher and senior author Qi Sun told the New York Post that the study found a “clear link” between exposure to these chemicals and a slow metabolism.
The study found that blood levels of PFAS were linked to greater post-diet weight gain in a group of 621 overweight or obese people. Levels of PFAS didn’t affect how much weight participants were able to lose on the study-prescribed diet, but rather how much weight they gained back after coming off the regimen.
“We all know it’s feasible to lose weight through diet or physical activity; however the challenging part is that almost no one can maintain that weight loss,” Sun told Health. “Now we’ve shown that PFAS level may actually determine how much weight people regain.”
Higher blood levels of PFAS were also linked to a lower resting metabolic rate, which Sun told Time could be “a very important part of the problem,” given the propensity for people with lower metabolic rates to accumulate body fat.
These findings were especially prevalent among female participants in the study.
“The sex-specific difference did surprise us a little bit,” Sun told Time. “But we also know that PFAS can interfere with estrogen metabolism and functioning, so this may be why we see this observation mostly in women.”
Previous studies have linked PFAS to hormone disruption, immune dysfunction, and even cancer.
PFAS can leach into the environment or into food, as shown by several previous studies including one 2017 paper published in Environmental Science & Technology Letters; this study also found that about half of 400 fast food containers tested contained indicators of the presence of PFAS.
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