What Are Obesogens? And Should I Be Avoiding Them?

Though countless magazine headlines and TikTok videos would have you believe otherwise, weight loss is not as easy as choosing the right supplement or juice cleanse. Likewise, obesity is a multifactorial problem that's often more complex than simply consuming too many calories or not having enough willpower. Research suggests that in addition to genetics, stress, illness, medication, lack of sleep and socioeconomic status, chemicals known as "obesogens" likely play a role as well.

"Obesogens are chemicals that could be linked to metabolic or hormonal dysfunction, which lead to obesity, among other health conditions," according to Michael L. Glickman, M.D., a family and obesity medicine physician in Washington, D.C., and the founder of the specialty practice Revolution Medicine, Health & Fitness. "We can be exposed to obesogens from the foods we eat, the liquids we drink, the products that we touch with our hands or skin, and the air that we breathe. We can even be exposed to obesogens before we are born, through a mother's blood that goes to the placenta."

Ben Bikman, Ph.D., a metabolic research scientist, co-founder of HLTH Code and professor at Brigham Young University in Provo, Utah, emphasized that obesogens are not classified as such because of their caloric value. A subset of endocrine-disrupting chemicals, they're not calories but molecules that stimulate the growth of fat cells and increase the amount of energy the body stores as fat. In doing so, they increase a person's susceptibility to weight gain throughout life, particularly if exposure occurs early while the body is still developing. They also interfere with hormones in other ways and can cause early puberty, infertility and other health issues.

Obesogens don't bear sole responsibility for the nation's obesity rate, which began to climb in the 1970s alongside changes in the food supply and the increased consumption of high-fructose corn syrup. However, research indicates a clear association between the increase in obesogens' ubiquity and obesity's prevalence. About 1 in 3 adults in the United States are overweight, and more than 2 in 5 people are classified as obese, according to the National Institute of Diabetes and Digestive and Kidney Diseases. About 1 in 11 adults suffer from severe obesity.

Here's what you need to know about obesogens, their effects and how to mitigate your risk.

The effects of obesogens on your sexual health

Although weight is not the sole determiner of health, carrying excess fat can increase a person's risk of conditions such as type 2 diabetes, heart disease, nonalcoholic liver disease and infertility.

"Obesity can significantly affect sexual health for both men and women in the form of reduced libido due to hormonal changes," Glickman said. "For men, in particular, excess body weight can reduce testosterone levels significantly. Erectile dysfunction is an extremely common symptom. Erectile dysfunction is often one of the earliest signs of developing heart disease. Plaque deposits in the penile artery are predictive of plaque deposits also developing in other places around your body, including the heart. ED is also caused by dysfunction of the inner lining of the blood vessels."

Obesity is associated with reduced sperm quality and quantity, Glickman continued. In women, it's often related to dysregulation of the hypothalamic-pituitary axis, which regulates sex hormones.

Carrying excess fat can increase a person's risk of conditions such as type 2 diabetes, heart disease, nonalcoholic liver disease and infertility.

"Imbalances of sex hormones lead to difficulties with ovulation and lower rates of implantation of an embryo into the uterus," he added. "Furthermore, women with obesity have higher rates of miscarriage and pregnancy complications that can affect both the mother and the baby. Fortunately, with healthy weight loss, this can often be reversible. Studies even show that modest weight-loss attempts prior to conceiving can increase the success rate of conception."

Aside from contributing to obesity, obesogens can directly disrupt metabolism, ovulation and the production of sperm and sex hormones, such as testosterone and estrogen, according to Bikman and Glickman. This disruption can lead to insulin resistance and fertility problems.

"The particular problem appears to revolve around their ability to mimic estrogens," Bikman said. "Not only can this cause obvious problems in men, whose estrogen levels are naturally quite low, but this also disrupts normal menstrual and ovulatory cycles in women, whose bodies are sensitive to the natural ebb and flow of estrogens throughout the month."

It's possible to pass obesogens from one generation to another. Research indicates people with obese parents are more likely to develop it themselves. This may be partly because obesogens in a pregnant person's bloodstream can infiltrate the placenta and reach the fetus, Glickman said.

What am I looking for?

More than 20 chemicals are classified as obesogens. While some, like bisphenol A (BPA), have been used in consumer products since the mid-1900s, their prevalence has risen exponentially over the past several decades, according to Glickman.

"Obesogens are becoming much more common," Bikman noted. "In fact, they would have largely been absent in the environment about 100 years ago. With the rise of processed foods and the reliance on plastics and detergents, these chemicals are increasingly difficult to avoid."

The most common types of obesogens are BPA, phthalates, certain pesticides and herbicides, and perfluorooctanoic acid (PFOA), according to Glickman. Some of these, such as BPA, have been extensively studied, but more research is needed to understand the full scope of effects they have on humans.

Bisphenol A (BPA)

Research indicates BPA, an endocrine-disrupting chemical that inhibits hypothalamic-pituitary axis function, may contribute to fat cell formation, oxidative stress, inflammation and insulin resistance. High levels of BPA have been linked to obesity, diabetes, high blood pressure and infertility in women.

"BPA, historically, is the most commonly used chemical, used to make plastics and resins that line food and drink containers, including cans or bottles, which can then leach out into the foods and liquids we consume," Glickman said. "We know this happens because we can measure blood levels of these chemicals in the population."

Although many food and beverage containers proclaim to be BPA-free, grocery store receipts are another significant source of exposure, as are PVC products such as cling wrap.

Phthalates

Glickman explained that phthalates are similar to BPA and used in plastics, including food packaging, toys, cosmetics and toiletries. They also can be found in dust particles.

The most prevalent type is Di (2-ethylhexyl) phthalate (DEHP), which binds to androgen receptors and interferes with testosterone synthesis, contributing to antiandrogen effects and obesity. Phthalates may directly impact metabolism.

High degrees of exposure have been linked to diminished sperm count and quality of sperm in men. In women, exposure is associated with oxidative stress, disrupted follicle growth and increased follicle death in the ovaries, all of which may contribute to infertility and reduced ovarian reserve.

Perfluorooctanoic acid (PFOA)

"PFOA is typically used as a surfactant in nonstick cookware and as a means to create waterproof clothing or furniture. Some of these chemicals—PFOAs in particular—have been labeled as 'forever chemicals' since they don't readily degrade in the environment and can be detected in our blood for years," Glickman noted. "These forever chemicals also end up in our water supplies and can be detected in drinking water reservoirs all over the world. Chemicals and microplastics can also be detected in our seafood supply around the world."

Canned and plastic-wrapped foods, including microwavable meals, and drinks in plastic bottles tend to be high in PFOAs, Glickman continued. However, most people are exposed through contact with contaminated water.

Like phthalates, PFOAs interfere with receptors in the body involved in metabolism. Studies on mice indicate exposure to PFOAs in utero correlates to a higher likelihood of obesity later in life, in addition to increased insulin and leptin.

Pesticides and herbicides

Pesticides and herbicides, such as atrazine and organotins, can be consumed in contaminated groundwater and foods.

Atrazine has antiandrogenic and estrogenic effects akin to those of BPA and phthalates. It also diminishes the production of luteinizing hormone (LH), which is essential for ovulation. Research suggests long-term exposure may increase the risk of obesity and insulin resistance. It may also increase the risk of congenital disabilities, gestational diabetes, diabetes and cancer.

Organotins, found in polyvinyl chloride (PVC) stabilizers, pesticides and certain paints, can seep into water supplies and aquatic life.

Animal studies suggest organotins may have endocrine-disrupting effects and stimulate fat cell production and storage. Research also indicates exposure to organotins in utero and through breast milk may predispose offspring to obesity later in life.

How to protect your health

To some degree, obesogens are unavoidable, but minimizing exposure could decrease your risk of serious effects.

"People who consume a diet that is high in processed foods—and, thus, have more exposure to plastics and packaging—as well as those who consume a lot of canned foods can be at a higher risk for obesogen exposure," Glickman explained. "In addition, those living in urban areas that have higher levels of air pollution can also be at a higher risk."

Glickman recommended minimizing the amount of processed, packaged and canned foods you consume as a good first step.

"A diet high in whole, plant-based foods that are organic and pesticide-free can improve metabolic health, help with weight loss, and reduce risks of heart disease and cancer," he said. "While no one can be perfect with their diet 100 percent of the time, even modest changes can go a long way. Drinking from a glass bottle rather than a plastic bottle can also help. To reduce the risk of air pollution, people can also purchase high-grade air filters for their home, such as a MERV rating of 13-plus."

Yelena Wheeler, R.D., M.P.H., a dietitian based in Los Angeles, noted that it's refreshing to see a greater appreciation for obesity's complexity. However, she cautioned that avoiding obesogens isn't a silver bullet against weight gain and associated health problems. She recommended taking a more holistic approach and implementing additional healthy habits, such as mindful eating, consuming plenty of protein and fiber, and honoring your body's hunger and satiety cues.

"As a dietitian, I caution against looking at obesogens as a magic explanation to a multilayered, complex problem," she said. "Obesity is an issue that not only stems from a metabolic/hormonal cause. Causation of obesity also has a psychological, economic and societal component. Therefore, addressing all causes of obesity, not just endocrine-disrupting chemicals, is the best path forward in the battle against obesity."