Obesogens

Obesogens are chemicals that can push the body to make and store more fat. You’ll find them in plastics, food packaging, cosmetics, pesticides, and some medications.

What Are Obesogens?

An obesogen is a substance from outside the body, usually a man-made chemical, that pushes the body toward storing more fat. Most belong to a larger group called endocrine disruptors, which copy, block or change the action of hormones.

Obesogens are one of the environmental causes of obesity that diet and exercise alone don't explain. Most researchers see them as one risk factor alongside diet, activity and genes, with the biggest effect when exposure happens early in life (Heindel et al., 2024).

The word "obesogenic" means something broader. It describes anything that promotes obesity. An obesogenic environment is a home, school or neighborhood that makes healthy eating and exercise harder, such as one with little fresh food nearby. Keep it, then add: An obesogenic diet is one built on calorie-dense, processed food.

How Do Obesogens affect the body?

Most of what we know about how obesogens work comes from cell and animal studies. In people, studies mostly show links between higher exposure and higher weight (Mohajer et al., 2021). Researchers have found five main effects:

• More fat cells. Some obesogens switch on PPARγ and RXR, two receptors that control fat cell development. This pushes stem cells to become fat cells instead of bone cells.
• Bigger fat stores. Existing fat cells take up and hold more fat.
• Changes to appetite. Some obesogens interfere with leptin and insulin, the hormones that signal hunger and fullness.
• Slower energy use. They can affect metabolic rate, mitochondria, and gut bacteria in ways that favor storing energy over burning it.
• Lasting effects from early exposure. Exposure in the womb or early childhood can change how genes are switched on. In mice, the effects of the chemical tributyltin showed up in later generations that were never exposed themselves (Egusquiza and Blumberg, 2020).

Common Obesogens List

Common obesogens, with examples of where you’ll find them:

Most obesogens in food come from packaging, pesticide residues, and contaminated water. A few occur naturally, such as genistein in soy.

Some prescription drugs have obesogenic effects too. Obesogenic medications include some antipsychotics, antidepressants, steroids and thiazolidinediones, a class of diabetes drugs. Don't stop a prescribed medication without talking to your doctor first.

Who Discovered Obesogens?

Paula Baillie-Hamilton is usually credited with first proposing, in 2002, that synthetic chemicals could be driving the obesity epidemic. She pointed out that the rise in obesity followed the rise in chemical production (Baillie-Hamilton, 2002).

The name came from Bruce Blumberg, a biologist at the University of California, Irvine, and his colleague Felix Grün. Their work on tributyltin, a chemical once used in boat paint, showed it activated PPARγ and RXR and made mice exposed before birth gain more fat. In 2006, they called chemicals that act this way "obesogens" (Grün and Blumberg, 2006).

How To Reduce Your Exposure To Obesogens

You can't avoid obesogens completely, but you can lower how much you take in each day. BPA and phthalates leave the body within hours to days, so levels can drop quickly. In a small study of 20 people, eating fresh food with little packaging for three days cut urine BPA by 66% and DEHP phthalate levels by about half(Rudel et al., 2011). PFAS are harder to clear, since some stay in the body for years.

• Store and reheat food in glass or stainless steel, not plastic.
• Eat more fresh food and fewer canned and packaged foods.
• Use a water filter certified to NSF/ANSI 53 or 58 for PFAS.
• Buy organic for the produce with the most pesticide residue.
• Choose fragrance-free personal care and cleaning products.
• Skip paper receipts when you can.
• Vacuum with a HEPA filter and dust with a damp cloth, since flame retardants collect in dust.

These steps matter most during pregnancy and early childhood.

What about an obesogens detox? Your liver and kidneys already clear the short-lived obesogens. No detox tea or supplement has been shown to remove them faster. Cutting down on new exposure is the approach with evidence behind it.