A study published January 26 in Environmental Science & Technology found that plastics found in everyday products like frozen meal packaging, yogurt containers, drink bottles, and even kitchen sponges may impact weight gain. “Our experiments show that ordinary plastic products contain a mix of substances that can be a relevant and underestimated factor behind overweight and obesity,” said Martin Wagner, PhD, a coauthor of the study and an associate professor at the Norwegian University of Science and Technology (NTNU) department of biology, in a press release.
Obesity Has Increased an Estimated 40 Percent in the Past 2 Decades
Obesity is a growing health crisis, both in the United States and around the world. From 1999–2000 to 2017–2018, obesity prevalence in the United States increased from 30.5 percent to 42.4 percent. During the same time, the prevalence of severe obesity nearly doubled, from 4.7 percent to 9.2 percent. No one thing causes obesity. It’s a combination of causes and individual factors including dietary patterns, genetics, physical activity, inactivity, and medication use.
Chemicals Found in Plastics Can Enter the Body
It was once thought that most plastic chemicals stay in the plastic. But in another paper Dr. Wagner coauthored that was published in August 2021 in Environmental Science Technology, plastic products were found to leach a large number of chemicals under real world conditions, therefore enabling them to enter the body. Bisphenols and phthalates are metabolism-disrupting chemicals (MDCs) that are frequently used in plastic products and have been shown to promote obesity in cell and animal models in the laboratory. Because these potentially concerning chemicals represent just a fraction of all the compounds found in plastic, investigators set out to further understand what other MDCs might be found in everyday products containing plastic and what impact they might have on fat.
Chemicals Found in Plastic Can Impact How the Body Manages Fat
According to an article in the March 2017 Reproductive Toxicology, metabolic disruptors are a category of endocrine disruptors that increase the susceptibility to metabolic diseases, including obesity, type 2 diabetes, and nonalcoholic fatty liver disease (NAFLD). The endocrine system is made up of glands that produce and secrete hormones that regulate all biological processes in the body from the time a person is born until they die, including metabolism and blood sugar levels, how the body processes and stores fat, and the growth and function of the reproductive system, according to the United States Environmental Protection Agency (EPA). Endocrine disruptors are chemicals that may mimic or interfere with the body’s hormones and that are linked with developmental, reproductive, brain, immune, and other problems, per the National Institute of Environmental Health Sciences.
Plastics Contained Chemicals That Increased the Number and Size of Mouse Fat Cells
The analysis included items such as yogurt containers, freezer bags, refillable plastic water bottles, and shampoo bottles — a total of 34 different plastic products in all. Investigators found more than 55,000 different chemical components in these products and were able to identify 629 of them. One-third of the plastic products investigated in the new study were found to contribute to fat cell development in laboratory experiments. The researchers found that the substances in the plastics reprogrammed precursor cells to become fat cells that multiplied and accumulated more fat. “By showing that chemicals extracted from commonly used plastic items increased the number and size of mouse fat cells in the lab, the study suggests that everyday exposure to these items — especially ones that store food, which can absorb chemicals from their containers — may be contributing to the obesity epidemic in humans,” says Linda G. Kahn, MPH, PhD, a researcher and an assistant professor in the departments of pediatrics and population health at NYU Grossman School of Medicine in New York City. Dr. Kahn was not involved in the research.
Researchers Found That Unidentified Chemicals May Also Contribute to Overweight and Obesity
The scientists observed that some of the plastic products that didn’t contain known MDCs still induced the development of fat cells, and concluded that many plastics contain currently unidentified chemicals that interfere with how our bodies store fat. It’s very likely that it is not the “usual suspects” that are causing these metabolic disturbances, said Johannes Völker, PhD, the first author of the study, who is affiliated with NTNU’s department of biology, in the release. “This means that plastic chemicals other than the ones we already know could be contributing to overweight and obesity,” he said. The discovery that these previously unknown chemicals might also be associated with weight gain makes this new research novel and notable, says Kahn. “These findings suggest that researchers need to expand their focus to incorporate a wider array of potentially obesogenic plastic chemicals in their studies of weight gain and metabolic dysregulation. Follow-up studies need to be done to see to what degree the plastic chemicals these researchers added to the fat cells in vitro actually migrate from the products in real-world scenarios,” she said.
How to Keep Plastic Out of Your Diet (as Much as Possible)
“The best way to minimize exposure to plastics through diet is not to purchase or store foods in plastic containers or wraps,” says Kahn. If that’s not doable, try to minimize the amount of time your food is in contact with plastic, and never heat food when it is in contact with plastic, she says. “That means not microwaving plastic containers and not letting plastic wrap touch the surface of your food when you microwave it,” adds Kahn.
