With the world on pace to have more than half its population overweight or obese by 2035, it’s time to look beyond the traditional causes – overeating and under exercising – to understand why. Action Alert!
Poor diet and a lack of activity are important factors in causing us to gain weight, as are our genetics, but scientists are also learning that chemicals we encounter every day change how our bodies process food. Certain endocrine-disrupting chemicals can promote fat cell growth, slow metabolism, and make it easier to put lost weight back on. While not the sole cause of the obesity epidemic, there are growing signs these chemicals do make us more prone to weight problems – and worsen things for people already struggling with them. As we’ve argued previously, the EPA isn’t doing enough to protect us from these disease-causing chemicals.
These chemicals, collectively called obesogens, exist all around us. They’re embedded in processed foods and their packaging, they coat our clothes and carpeting, fill the oceans, and even linger in dust particles that float in our homes. In the decades that these chemicals have become ubiquitous, so has the obesity problem. Rates have tripled in the last half century, hitting young people especially hard, and many other species of animals are getting fatter now too. It’s an area ripe for more research, but what we know already suggests that the greater our exposure, especially in critical stages of development, the greater the risk of a lifetime of weight management problems.
The study of obesogens is relatively new, with the first paper suggesting chemical exposure contributes to obesity published in 2002, and the term itself coined four years later by cell biologist and obesogen pioneer Bruce Blumberg, PhD. In the same ways carcinogens promote the growth of cancer cells in living tissue, obesogens include any environmental chemical that can increase white fat tissue in the body. They can also alter the gut microbiota and shift energy balance to make our bodies burn fat slower and adjust our hormones to make us hungry more often. The exact number of obesogens is still a mystery – with many chemicals still unexamined – but scientists have already identified several dozen types, with thousands more potentially meeting the criteria. Some of the most common known or suspected obesogens include:
Per- and polyfluoroalkyl substances are used in everything from food packaging and personal care products to nonstick cookware and stain-resistant clothing because they resist heat, water, grease and oil. Known as forever chemicals because they don’t break down in the environment or our bodies, they’ve been associated with a higher risk of childhood obesity and a greater body mass index (BMI) later in life for people exposed to them as children.
An additive used to make plastics softer and more durable, phthalates are common in, among many things, cosmetics, vinyl flooring, food storage containers, and the medical-grade tubing and fluid bags used in hospitals. They are also frequently found in common house dust. Phthalates disrupt testosterone synthesis and contribute to obesity. When researchers checked people’s blood for these chemicals, they found high phthalates concentrations correlated to a proportionally higher BMI.
Bisphenol-A, commonly called BPA, lines many types of food and beverage containers and can leach into the products in extreme temperatures. It’s also in thermal paper, such as cash register receipts, which absorbs, through touch, into our skin. Studies have found that even in low doses, BPA can disrupt metabolism and increase the risk of childhood obesity.
These compounds used in pesticides, certain paints and hard plastic food packaging can promote fat cell production and cause fat to accumulate while reducing muscle mass. One of the most-studied types of organotins, tributyltin, is an ingredient in special paint that stops algae, barnacles and other organisms from growing on the hulls of ships. It was banned for use in small craft in the 1980s because it contaminated waterways and the fish we eat from there, but this paint is still used on some larger vessels.
- Fructose and Artificial Sweeteners
Fructose is naturally part of fruit, honey and other foods, it and signals the body to start storing fat or glycogen. Inexpensive sweeteners made from high-fructose syrups are commonly used to make soft drinks, cereals and other products taste better, but studies have documented how they contribute to weight gain. Artificial sweeteners, developed as sugar alternatives, still raise insulin levels, can change the gut microbiome and have been shown to increase body fat in lab animals.
Critics have long argued that much more research is needed, and that lab animals get proportionally higher doses of these chemicals than we get from our environment. While that might be the case for a one-time exposure, we’re around these chemicals all the time. We’re dosed every day by just living our lives, possibly from things we’re not even aware are dangerous yet. We also don’t fully understand how all these chemicals interact inside our bodies, something more research would help discover.
Tough To Study
One main reason there hasn’t been more human research is because obesogens pose a special challenge. These chemicals are abundant and hard to isolate, they include hundreds of potential types, and it would be unethical to give them to human test subjects. Further complicating matters is that companies who make and use these chemicals hide many basic details about them behind trade secret privileges, and government regulations give many of their products a presumption of safety.
These challenges have restricted most obesogen research to animal tests, but these tests still tell a potent story. Mice fed a common phthalate, DEHP, had more voracious appetites and packed on more belly fat than those who weren’t. Lab animals exposed to PFOA, the forever chemical used in nonstick cookware for decades, had a higher risk of developing obesity and diabetes. Animal studies have shown that some obesogens build up in the subject’s tissues, while others pass an inclination toward obesityon to their offspring.
It’s not too much of a stretch to think that effects on humans will be similar. After all, common medications for depression and diabetes have been shown to make patients gain weight. Scientists have also seen weight gain correlations when they measure chemicals already in people’s blood. In one study involving hundreds of dieters, those with the most PFAS in their systems ultimately regained more weight once the diets ended. Another human study found correlations between higher PFAS levels and a slowed metabolism.
What We Can Do
We’ll never be able to avoid all obesogenic environmental chemicals – that can be as hard as having dust-free air in our homes. But we can make changes to avoid some of the most common products, such as swapping processed foods for fresh alternatives, using glass containers for food storage, never reheating food in plastic bags or cartons, and avoiding flexible plastic water bottles, nonstick cookware, and flame- and water-resistant coatings on carpets, furniture and clothes. We can also look for products made without phthalates or BPA, although some BPA alternatives have issues of their own.
It’s also time to urge the Food and Drug Administration and Environmental Protection Agency to improve their outdated chemical assessment protocols and fund more research into obesogens, how they affect people, and which chemicals pose the biggest threat. They must stop letting chemical users and producers police themselves and hide behind laws that shield basic facts from the public. The law itself is also broken, allowing the EPA to take action against a chemical if it is found to present an “unreasonable risk of injury to health,” a term which is not defined. This standard was designed to limit action against harmful chemicals: the burden of proof was so difficult that the EPA couldn’t ban asbestos, a known carcinogen that kills 15,000 people a year.
Obesogens aren’t the sole cause of the world’s expanding waistline, but they’re factors we shouldn’t just have to tolerate.
Action Alert! Write to the EPA and Congress, urging them to define “unreasonable risk to human health” and ban the chemicals that are helping to drive the obesity epidemic . Please send your message immediately.