April 26, 2023 -- Heavily used “forever chemicals” found in food packaging and other consumer goods are contributing to weight gain, a new study has found.

The study focused on PFAS (perfluorinated alkylate substance) exposure. It was published in the journal Obesity.

“They are colorless, tasteless, and odorless, and often are used to create barriers or stop liquids from seeping,” the University of Rhode Island said in a press release. “The chemicals coat pizza boxes and microwave popcorn bags, nonstick cookware, and waterproof clothing, and stop stains from sinking into carpet and furniture.”

The chemicals have leached into water, “from marine habitats to drinking water resources,” the release said.

Higher PFAS levels in blood promote weight gain and make it harder for people to maintain a weight loss, the researchers found. Earlier studies showed PFAS contributed to weight gain and high cholesterol levels in children, the release said.

“We now focused on adults who participated in an experimental study of five different diets in regard to weight gain,” said Philippe Grandjean, MD, who has a research professor appointment within the URI College of Pharmacy. “Our results add to the concern that environmental pollution may be affecting our metabolism, so that we tend to gain weight.”

Researchers examined PFAS chemicals in 381 blood samples that were already part of a randomized European Commission clinical trial in Europe focused on weight loss planning for obese adults.

“No matter the diet that these participants were assigned to, they gained weight if they had elevated PFAS exposures,” the release said.

The study’s authors wrote, “baseline plasma PFAS concentrations were significantly associated with greater weight gain by 26 weeks after an initial weight loss.”

They said future dietary trials should consider PFAS exposure to improve precision.