There are many artificial chemicals believed to contribute to obesity.
These chemicals are termed "obesogens" - foreign chemical compounds that can disrupt the normal function of the body and cause fat gain ().
They are found in various food containers, baby bottles, toys, plastics, cookware and cosmetics.
Many of them are classified as Endocrine Disruptors - chemicals that can interfere with your hormones ().
These chemicals exert their effects by activating estrogen receptors, which can cause harmful effects in both females and males.
The estrogen receptor is "promiscuous" - meaning that it will bind to anything that looks even remotely like an estrogen ().
These substances have not only been linked to obesity, but also to birth defects, premature puberty in girls, demasculinization in men, breast cancer, and various other disorders.
Unfortunately, many of these effects happen in the womb.
Pregnant women are exposed to these chemicals, which changes the epigenetic "programming" of the fetus, the child then being at a much greater risk of becoming obese later in life ().
There are now 20 chemicals that have been identified as obesogens and it is beyond the scope of this article to cover all of them.
However, I decided to cover those who I think are the most important.
Here are 5 of these "obesogenic" chemicals, which are present in your home at this very moment.
Bisphenol-A (BPA) is an synthetic compound that is found in many types of products.
This includes baby bottles, plastic food and beverage containers, as well as metal food cans.
It has been in commercial use for many decades, but recent studies have shown that it may cause significant harm to both lab animals and humans ().
BPA is structured in a way that mimics the natural hormone estradiol, a female sex hormone.
Inside the body, BPA binds and activates estrogen receptors ().
It appears that the time of greatest sensitivity to BPA is in the womb and 96% of pregnant women in the USA test positive for BPA in their urine ().
Multiple studies have associated BPA exposure with weight gain and obesity, in both lab animals and humans (, , , ).
One study in cell culture discovered that BPA increased both the number of fat cells, as well as the amount of fat that the fat cells produced and held on to ().
BPA exposure has also been linked to insulin resistance, cardiovascular disease, diabetes, neurological disorders, thyroid dysfunction, cancer, genital malformations and a lot more (, , , ).
I'd like to point out that not all scientists agree that BPA causes harm. The regulatory authorities in the United States and European Union don't believe that it causes harm, or at least that it isn't proven yet (, , ).
I don't know about you but I personally don't have much faith in the regulatory authorities. These are the same people that told us that trans fats were safe and still say that sugar is just empty calories.
Other countries, including Canada and Denmark, find the evidence convincing enough that they've set laws to reduce the amount of BPA in consumer products.
I have listed some methods to minimize your exposure to BPA (and the other obesogenic chemicals) at the bottom of the article.
Bottom Line: Bisphenol-A (BPA) has been linked to obesity and many other diseases in humans, although not all scientists agree that it causes harm. It is primarily found in plastics and canned foods.
Phthalates are chemicals that are used to make plastics soft and flexible.
They are found in various places, including food containers, toys, beauty products, pharmaceuticals, shower curtains and paint.
These chemicals can easily leach out of plastics and contaminate foods, the water supply and even the very air we breathe ().
A Swedish study found that children can absorb airborne phthalates from plastic floor material through the skin and respiratory tract ().
In a study by the CDC, most Americans tested positive for phthalate metabolites in their urine ().
Like BPA, phthalates are endocrine disruptors, changing the function of hormones in our bodies (, ).
Phthalates may be contributing to increased susceptibility to weight gain by affecting hormone receptors called PPARs, which are intimately involved in metabolism ().
Multiple studies in humans have shown that phthalates levels in the body are associated with abdominal obesity, increased waist circumference and insulin resistance, especially in men (, , ).
It appears that males are particularly susceptible. Studies show that phthalate exposure in the womb leads to genital malformations, undescended testes and low testosterone (, , , , ).
One study found that phthalate metabolites in the blood correlated with type II diabetes ().
Many government and health authorities have begun taking action against phthalates, with the state of passing laws that instruct toy manufacturers to stop using phthalates in their products.
Bottom Line: Phthalates are chemicals found in many plastic products. Some studies show a link between phthalate exposure and obesity, type II diabetes and genital malformations in boys.
Atrazine is one of the most widely used herbicides in the United States.
It has been banned in Europe for over a decade because of groundwater contamination ().
Atrazine is an endocrine disruptor and several studies show that Atrazine exposure correlates with birth defects in humans (, , ).
In the USA, there is an overlap between the areas that use the most Atrazine and the prevalence of obesity.
It has been shown to damage mitochondria in rats, decreasing the metabolic rate and increasing abdominal obesity ().
Of course, correlation does not equal causation and we're still a long way off from proving that Atrazine is a significant contributor to obesity in humans.
Bottom Line: Atrazine is a commonly used herbicide. There is some correlation between Atrazine use and the prevalence of obesity. Studies in rats show that Atrazine can damage mitochondria and cause obesity.
Organotins are a class of artificial chemicals used for various industrial purposes.
One of them is called tributyltin (TBT), which is used as a fungicide and applied to boats and ships to prevent growth of marine organisms on the hull.
It is also used in wood preservatives and some industrial water systems.
Tributyltin is harmful to marine organisms and has been banned by various regulatory authorities ().
Many oceans and lakes are contaminated with tributyltin (, ).
Some scientists believe that tributyltin and other organotin compounds can function as endocrine disruptors and contribute to obesity in humans by increasing the number of fat cells ().
In one study, tributyltin was found to induce the proliferation of fat cells and reduce their production of leptin in a test tube ().
In another study in mice, tributyltin exposure for 45 days caused weight gain and fatty liver disease ().
There is also evidence that exposure to tributyltin in the womb sends signals to multipotent stem cells to become fat cells, which may lead to a significant increase in fat mass over time ().
Bottom Line: Organotins, including tributyltin, are compounds that have been shown to cause weight gain and fatty liver syndrome in mice. They may signal to stem cells to turn into fat cells.
Perfluorooctanoic Acid (PFOA) is a synethetic compound used for various purposes.
It is a constituent of non-stick cookware made with Teflon and also found in microwave popcorn ().
PFOA has been found in the blood of more than 98% of the U.S. population ().
It has been associated with various diseases in humans, including thyroid disorders, low birth weight and chronic kidney disease (, , , ).
In one study in mice, exposure to PFOAs during development lead to increased insulin, leptin and body weight during mid-life ().
Whether PFOAs really contribute to obesity in humans remains to be seen.
Bottom Line: Perfluorooctanoic acid is found in non-stick cookware and various other products. It is also associated with various diseases in humans and one mice study shows that prenatal exposure leads to obesity in mid-life.
There are many endocrine disrupting chemicals and covering all of them is beyond the scope of this article.
It is downright impossible to avoid them completely, because they are literally everywhere.
However, there are a few simple things you can do to dramatically reduce your exposure and minimize your risk of later complications.
- Eat organic produce and naturally raised/fed animals.
- Avoid foods and beverages that have been stored in plastic containers.
- Use stainless steel or quality aluminum water bottles .
- Parents, do NOT feed your babies from plastic bottles. Use glass bottles instead.
- Instead of non-stick cookware, use cast iron, ceramic or stainless steel.
- Use organic, natural cosmetics.
Of course, eating healthy, exercising, getting quality sleep and avoiding stress are still the most important factors when it comes to your health.
Only you can decide whether going through extreme lengths to avoid these chemicals is worth the inconvenience and extra cost.
But if you are a pregnant woman or plan on becoming pregnant, then I think it is crucial that you do your best to avoid being exposed to these chemicals. It could have a dramatic effect on the future health of your baby.
It's important to keep in mind that the effects of these chemicals are far from being proven. Most of the data is observational and based on studies in lab animals.
I do not know whether these chemicals will ever be proven to cause harm, but I am personally not going to wait around for that to happen.
It's better to be safe than sorry.