A new study from researchers at Harvard University has shown that certain chemicals used in consumer products as well as industrial products are linked to obesity and weight gain. The chemicals under the scanner are perfluoroalkyl substances (PFASs). These PFAs have been linked to raised cholesterol, hormone imbalance, immune problems, cancers and obesity.
The study titled, “Perfluoroalkyl Substances and Changes in Body Weight and Resting Metabolic Rate in Response to Weight-Loss Diets: A Prospective Study,” appeared yesterday (13th of February 2018) in the latest issue of the journal PLOS Medicine.
The team of researchers calls these chemicals “obesogens” because they serve to disrupt the regulation of body weight. These PFAs lower resting metabolic rate (RMR). This reduces the burning or using up of the calories. These excess calories then tend to get stored as fat. To avoid becoming fat, people with a low RMR need lower calorie intakes.
Lead author Qi Sun, assistant professor in the Department of Nutrition at Harvard Chan School explained that these obesogens are associated with obesity and excessive weight gain among animal models of obesity. Human studies are unavailable at present. This study thus addresses this gap and proves a novel mechanism by which PFAs can disrupt body weight regulation and lead to the rising number of obese individuals. The team from Harvard Chan School collaborated with other researchers from Louisiana State University and Tulane University.
The authors explain that PFAs have been used in various products over the last six decades. These are part of food wrappers, pots, pans and some clothing too. Industrial wastes containing PFAs are known to contaminate drinking water and find their way into human bodies. These are known to remain in human bodies for a very long time.
The team of researchers looked at 621 overweight and obese individuals. They named their study Prevention of Obesity Using Novel Dietary Strategies (POUNDS LOST) clinical trial. The study started in mid-2000s looking at the effects of four types of heart-healthy diets on weight loss over a period of two years. In the latest study the same data was used to see the effect of PFAs on weight gain and obesity among these individuals.
Results revealed that –
- Weight loss over first six months was an average 6.4 Kg but over the next 18 months the weight gain was 2.7 Kg.
- Blood concentration of PFAs was highest among those who gained most weight during the 18 months.
- Women tended to be the highest gainers. Women who had the highest levels of blood PFAs tended to regain 1.7-2.2 kg more body weight compared to women who had the lowest amounts of PFAs in their blood.
- Raised levels of PFAs in blood was associated with lower RMRs
Co-author Philippe Grandjean, adjunct professor of environmental health at Harvard Chan School said that PFAs and their association with cancer has been known and feared for some years now. However this new study throws light on the other health problems that can be associated with these chemicals. Obesity is a major health problem globally he said. He said that reducing exposure to PFAs could help the population, especially women, to maintain stable body weights after weight loss.