Fat Cats Support Theory that Chemicals Make Us Fat

Health & Wellness on 02.13.12
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Image: -Tripp- /CC BY 2.0

Everyone knows that portion sizes have increased and activity has decreased in our modern age. Added sugars, junk food that is cheaper than real food, and lack of physical activity seem obviously to blame in the obesity epidemic. But if our lazy, super-sizing habits are the source of our extra pounds, why is the cat getting fatter too?

In fact, studies show that our pet dogs and cats, as well as rodents and primates living in carefully controlled conditions in research labs, are all gaining weight. What are the chances this is a coincidence? Less than 1 in a million, according to Yann Klimentidis and colleagues who worked on one study on the cross-over of the obesity epidemic in other species.


The word "obesogens" sounds like it might describe an unavoidable curse written by fate into our DNA. But the word should be read more like “pathogens” than “fat genes.”

The term is attributed to Bruce Blumberg, a biologist who discovered that mice babies were fatter when born after their mothers were exposed to tributyl tin (TBT, now banned as a marine antifouling agent but still used in environmental applications such as wood treatment). 

Basically, obesogens are chemicals which send messages to our bodies which cause them to retain weight or even reset metabolic processes.  Obesogens dial up “11” on the fat amplifier, in short. Exposure does not condemn us to a lifetime of being overweight, but it makes taking weight off, and keeping weight off, harder.

Which Chemicals are Obesogens?

The mug shots in the line-up of characters which might be adding secret pounds come straight out of the file of usual suspects marked "endocrine disruptors." Chemists and toxicologists have become increasingly concerned about these chemical messengers, which can cause major changes in body chemistry with even minor exposure.

Some of the higher profile chemicals now suspected of being obesogens include:

  • Atrazine, banned in Europe but still one of the most widely used herbicides in the world
  • Breakdown products of DDT - the Silent Spring insecticide, widely restricted but still used to control insect-transmitted diseases and still present in the environment due to past use and contamination from disposal sites.
  • Organotins, including dibutyl tin which is used as a stabilizer in PVC (vinyl, or fake leather)
  • Phthalates, which stabilize plastics and are also commonly found in products with fragrances, such as air fresheners, laundry products, and lots of items on the bathroom shelf.
  • Bisphenol-A (BPA), found in plastic bottles, cash-register receipts, and tin can linings
  • Perfluorooctanoic acid (PFOA), used in coatings for non-stick and water repellent properties
  • Even dietary sources such as soy phytoestrogens or monosodium glutamate (msg) are implicated in weight gain.

Some chemicals cause babies to be born underweight, after which their bodies play a sort of catch-up, eventually overshooting on the high weight side. These include by-products of cigarette smoke and DES, a now discontinued synthetic estrogen used from the 1930s through the 1970s to prevent miscarriage.

The list continues to grow, with the National Institutes of Health offering grants to scientists for studies linking environmental exposure to chemicals to weight gain, Type 2 diabetes, or metabolic syndrome.

A recent article in Environmental Health Perspectives offers further reading and an excellent overview of the state of science on the question of an environmental link to obesity.

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