In the last decade or so, animal studies have increasingly indicated that certain chemicals, particularly those already known to be endocrine (hormone) disruptors, can lead to obesity.
Turn On the Fat Cell Development
Research started with tributylin (TBT), used to paint the underside of ships to prevent barnacles from growing there. The studies showed that TBT activates a fatty acid receptor, which regulates fat cell development. Sure enough, animals who had been exposed to TBT, particularly in utero, grew up to be fatter than their ancestors.
Other endocrine disrupting chemicals that behave this way include the pesticides DDT and PCBs, tolyfluanid, a flame retardant called 2,2′,4,4′-tetrabrominated diphenyl ether, or BDE-47, phthalates, found in plastics, and triflumizole, a fungicide.
You can avoid PCBs by buying your fish wild-caught, and DDT, triflumizole, and tolyfluanid by buying the Dirty Dozen fruits and veggies organic.
To avoid flame retardants, follow this excellent advice from the Environmental Working Group.
Avoid phthalates by choosing glass or pyrex storage containers rather than plastic tupperware, choose glass or stainless steel water bottles instead of plastic ones, and skip the seran wrap in the microwave—use a paper towel instead to avoid splatter.
Crank Up the Cortisol
Cortisol is an adrenal hormone that helps us deal with stress—but it also breaks down glycogen and initiates gluconeogenesis in the liver, both of which increase circulating glucose. Glucose (sugar) in excess of our metabolic needs then gets stored as fat, and this leads to both obesity and insulin resistance.
Obesogens that can make you fat via excess cortisol include DDT, PCBs, and tolyfluanid again, as well as endrin (another pesticide), and Bisphenol A (BPA) and phthalates, both found in plastics. BPA also is found in the lining of canned foods.
You can avoid BPA by skipping canned foods (even those that boast they are BPA-free have a chemical in the bisphenol family instead).
Bring on the Insulin Resistance
Some obesogens cause insulin resistance more directly, by decreasing the production of members of the insulin signaling cascade. (What that means: signaling in your body is kind of like a Rube Goldberg machine, where one thing triggers another triggers another. Here’s a fun YouTube video to give you a visual!)
Chemicals that do this include tolyfluanid again.
Estrogen Dominance Anyone?
Xenoestrogens, or chemicals that act like estrogen in the body, can also pack on the pounds. This study and this study both demonstrate that BPA can do this—but the heavy metals cadmium, arsenic, and lead can do the same. Here are a list of other xenoestrogenic chemicals as well.
Avoid cadmium by not smoking and protecting yourself from secondhand smoke.
Avoid arsenic by (sadly enough) skipping the non-organic chicken!
Lead is more regional; very old pipes or houses with very old paint can be toxic sources.
Where is The EPA?
As it turns out, the United States Environmental Protection Agency (EPA) has not attempted to ban any chemicals at all since the 1980s, despite plenty of evidence that some chemicals cause us harm! This is apparently because despite a decade of lobbying to ban asbestos, a known carcinogen, they were ultimately overruled by bureaucratic red tape. After that, I guess they figured, why bother?
The Upshot on Obesogens
So it’s up to you and me to limit our exposure to these chemicals. More severe exposures, or people whose livers are not as efficient at detoxing as they should be, may need a full cleanse protocol. But for most of us, avoidance goes a long way.