Obesogens: Nature’s Fattening Agents

The formula for losing weight hasn’t changed in forever. It’s

Calories in < Calories out.

This is still true today, but increasingly it has a curious twist.

Your body’s propensity to burn calories and store fat are modified not only by the food you eat, but by chemicals ingested through the environment.

They’ve been termed “obesogens” by many, and the truth is there’s a large number of chemicals that can alter your body’s metabolism at a high enough dosage.

What’s bad about obesogens? They make you fat in the following ways:

• They decrease your body’s base metabolic rate
• They encourage your body to form fat cells
• They mimic estrogen, and mess up sex hormone regulation
• Exposure to obesogens in the womb can significantly alter someone’s thyroid, metabolism, and hormonal function for life.

Not pretty.

Types of Obesogens

Obesogens generally fall into three different categories: xenoestrogens, phthalates, and organotins.

Here’s a quick brief on how they work:

Xenoestrogens: Compounds that are similar to estrogen in structure, and stimulate sex hormones in the same way. A little bit of estrogen is good of course, but getting more than you need is a big problem.

Excessive exposure to xenoestrogens can cause infertility, a malfunctioning reproductive system, and stimulate the formation of fat cells.

Organotins:  Organotins are compounds that contain a tin and hydrocarbon molecule. They’re frequently used in pesticides, herbicides, fungicides, and generally any compound that ends in “icide.” Organotins come in a variety of forms, but it’s the kinds that begin with the suffic “tri” that cause problems in the body.

Phthalates: Phthalates are chemicals used to soften plastics and are used as intermediaries in other sorts of adhesives and carbon based compounds. They’re not added to food directly, but they don’t bind with the plastics they soften and bounce off into other substances. Many industrial processes indirectly add phthalates to food, and food consumption is the biggest source of ingestion.

With that in mind, let’s take a look at the six most common obesogens, where they’re found, and what they can do in your body.

1). Bisphenol A (BPA)

The Skinny: Bisphenol A is a ubiquitous xenoestrogen that’s used to treat PVC plastics of all sorts. In some studies it’s been shown to increase insulin resistance and upregulate different gene networks that promote fat cell formation by activating different endocrine receptors in the body….similar to estrogen.

Important Facts: Bisphenol A is found virtually everywhere, but infants have the most regular exposure to BPA, which is troublesome. In quite a few studies prenatal exposure to BPA has been shown to impair neurological development.

Rats that are treated with BPA in infancy typically have a lower than normal bodyweight and increased metabolism, which causes the body to lower its “set point” for burning calories, which can persist later on into life.

BPA can generally be found in any plastic that’s 1,2,4,5,6 recyclable.

2). Nonylphenols

The Skinny: Nonylphenol is a xenoestrogen that’s commonly used in detergents. It’s not as potent as other obesogens because it’s structural similarity to estrogen isn’t very high. For this reason, it’s typically dangerous only with continuous high dosage, which admittedly is pretty rare.

Important Facts: Long term data on nonylphenols ingestion and toxicity rates is pretty scarce. However, it’s commonly found in sewage water outside of different factories and industrial plants.

Studies done on the fish that live downstream of these establishments compared to those that live upstream have shown the fish with regular exposure to nonylphenols have impaired reproductive systems and metabolic stress.

3). Tributylin Oxide (TBT)

The Skinny: TBT is an organotin that’s commonly used in wood preservation. In the body it can stimulate different genes that tightly control the size, number, and health of fat cells…..in the wrong direction. It does this by activating nuclear receptors that have the title RXR/PPAR, which upregulate different metabolic networks that control cellular metabolism.

Important Facts: TBT seems to be ingested into the fetus fairly regularly during pregnancy, where it can cause the overproduction of corticol compounds, which leads to weight gain later in life.

4). Triphenyltin (TPT)

The Skinny: TPT is the molecular cousin of TBT, and works in a similar way in the body. However, it’s more commonly used in pesticides and fungicides.

Important Facts: A few studies have been done on ingestion levels of TBT and TPT, and results vary. Estimates on the low end begin at 0.7 ng, and go up to 8ng/ml. Only one of these studies has been conducted in the United States, and in general the data on TPT ingestion is sparse.

However, these estimates are generally in the range required for TPT and TBT to be biologically active.

5). Perfluorooctanoic Acid (PFOA)

The Skinny: PFOA is a phthalate used in lots of aerosols and surfactants. It often gives cleaners and polishes the ability to give surfaces a “smooth” feel. Like TBT and TPT, PFOA activates the PPARa receptor in cells, which regulates how fat cells behave in the body. It’s been estimated that total ingestion of PFOA is 160 ug/day, which is generally enough to be biologically active. 75% of Americans have phthalate metabolites in their urine.

6). DEHP

The Skinny: DEHP is a phthalate that’s commonly consumed through food. When it comes in contact with plastic it’ll often leach off the surface and into nearby substances. Like other phthalates, prenatal exposure has curious effects on infant body weight, metabolism and sexual dysfunction.

In one particularly scary study, infants exposed to DEHP in the womb later had reduced penis size and less potent testes. In epidemiological studies higher levels of DEHP have been linked to increased obesity and insulin resistance in men.

Dangers, Dosage, and Infants

Pointing out that a certain substance can be toxic if consumed in large enough quantities is not dangerous all by itself. After all, every compound is toxic if consumed in large enough levels.

The real question is how much do most people typically consume everyday, and if that amount is enough to allow these compounds to be biologically active within the body.

That’s the million dollar question, and it’s still unsolved right now.

However, it’s important to be aware of these environmental elements, and at least incorporate them into your decision making.

Especially if you’re pregnant.

Research and References:

Blumberg, Bruce, et. al. “Minireview: The Case for Obesogens.” Molecular Endocrinology. August 2009. Pgs. 1127-1134

URL: http://mend.endojournals.org/content/23/8/1127.full#ref-73

National Toxicology Program, U.S. Department of Health and Human Services. CERHR Expert Panel Report for Bisphenol A [PDF].. 26 November 2007

Pelley, Janet. “Plasticizer May Make Boys Less Masculine.” Environmental Science and Technology. November 12, 2008.

URL: http://pubs.acs.org/action/showStoryContent?doi=10.1021%2Fon.2008.11.12.154968&

Blumberg, Bruce. “Endocrine Disruptors as Obesogens.” Molecular and Cellular Endocrinology. May 2009. Pgs. 19-29.

URL:  http://www.sciencedirect.com/science/article/pii/S0303720709001488

Golden RJ, Noller KL, Titus-Ernstoff L, Kaufman RH, Mittendorf R, Stillman R, Reese EA (March 1998). “Environmental endocrine modulators and human health: an assessment of the biological evidence”. Crit. Rev. Toxicol. 28 (2): 109–227