What To Know About Obesogens

Medically Reviewed by Melinda Ratini, MS, DO on August 10, 2023
4 min read

Over the years, human body weights have trended higher. Some of that can be attributed to positive changes, such as consistent access to enough food. But other factors have been linked to excessive weight gain, such as heavily processed foods with higher concentrations of sugars and fats than what your body needs.

An increasing number of people find that their weight is above the range that would typically be considered healthy. About 42% of Americans are considered obese, according to the Centers for Disease Control and Prevention. Experts are struggling to understand why people have trouble losing weight, even when they want to do so.

Some researchers suggest the possibility that chemicals in common products may contribute to obesity. These chemicals may affect human hormones and change the way our bodies make, store, and use fat. Experts call these chemicals obesogens.

In the past, experts believed that weight gain was a result of eating more calories than your body needed to function. Excess energy from food is stored in our bodies as fat, so the idea is that eating more than you need results in fat gain. In recent years, doctors have found that sometimes people who change their eating and activity levels still don’t lose weight.

One possible explanation for this inability to lose excess weight is metabolic changes caused by exposure to chemicals. For several decades, researchers have noted that lab animals gain weight when they are exposed to specific substances. Scientists realize now that those substances are endocrine disruptors, which means these chemicals affect the normal function of hormones in animals and people.

Early research suggests that there are several ways that obesogens affect your body, including:

Increasing fat cells. Some obesogens can trigger your body to make new fat cells. In some cases, the new cells may be unusually large. This allows more fat to build up in your body, leading to weight gain. The research on this isn’t conclusive, and scientists are continuing to study this process in humans and animals.

Blocking fat burning. Obesogens may disrupt the usual way fat cells work so that they can’t release stored fat. If your body can’t access fat to use as energy, the fat stores never go down. This may explain why changing food and exercise levels does not affect how much fat your body has. Research into this process is ongoing to understand better how obesogens limit fat loss.

Altering appetites. Some obesogens may affect your hypothalamus, the part of your brain that controls appetite. The hypothalamus releases hormones that signal hunger and other hormones that tell you when you’re full. In animal studies, certain chemicals affected that process. The animals showed a tendency to compulsively eat and not stop even if they might not be hungry anymore. This may happen to humans, as well.

Scientists have identified quite a few chemicals that may be obesogens, but the research is not yet conclusive. Some of the substances are already prohibited because of health concerns. Others are commonly used in manufacturing, agriculture, and consumer goods.

Phytoestrogens. Phytoestrogens are found in food products, including soybeans, lentils, and chickpeas.

Organotins. These chemicals are fungicides. They are used in treating wood for building materials.

Polycyclic aromatic hydrocarbons (PAHs). PAHs are byproducts caused by the burning of some types of fuel. They result in air pollution.

Bisphenol A (BPA). BPA and similar chemicals are used in plastics. They are found in food and beverage containers.

Polybrominated diphenyl ethers (PBDEs). PBDEs are flame retardants. They are used to treat materials such as fabrics or furniture to make them less likely to catch fire.

Phthalates. Phthalates are plasticizing agents. They are found in cosmetics, medicines, and paint.

Parabens. Parabens are preservatives found in food, paper products, and medicines.

Pesticides. Pesticides used in agricultural industries may have obesogenic effects.

Alkylphenols. These are a type of surfactant and thickener that are used in many consumer goods, such as rubber or paint.

There is evidence that some medications may have an obesogenic effect. Thiazolidinediones, atypical antipsychotics, antihistamines, and antidepressants may have effects that lead to weight gain or difficulty losing weight.

Researchers do not have conclusive results from studies about the effects of obesogens. There are still many questions about obesogens and how they affect human beings. If you are concerned about exposure to obesogens, you can make lifestyle changes to protect yourself.

Caution during pregnancy. There is some evidence that obesogens can affect babies while they are in the womb. Avoiding obesogens during pregnancy may help your baby.

Ingredients. Most foods and many household products have ingredient lists on the containers. You can look at these for more information about possible obesogens in foods or personal care products.

Packaging. Some experts suggest that avoiding plastic packaging can reduce your exposure to obesogens. In addition, you may want to limit your handling of certain types of paper, such as the paper for printed receipts. They can be treated with plastic-like coatings made from BPA.

Air pollution. You can limit the amount of air pollution that comes into your home by removing your shoes when you're indoors. Using HEPA filters and vacuuming frequently may also be helpful.