Warning: Drinking Bottled Water Could Make you Fat!

By Chris Kresser, “The Healthy Skeptic”

I came across some interesting research the other day concerning the potential role of Bisphenol-A (BPA) in regulating weight.

BPA is a chemical that is found in several plastics and plastic additives. It’s in the water bottles folks carry to gyms and in the baby bottles moms use to feed their infants. And it’s in almost all of our bodies.

A CDC study in 2007 found that 92% of 2,500 subjects studies had detectable amounts of BPA in their urine.

A study published in 2002 by Masuno and colleagues demonstrated that relatively small amounts of BPA significantly reduced insulin sensitivity and accelerated the formation of adipocytes (fat cells). In other words, BPA made the mice fat.

Not only did BPA trigger the conversion of pre-adipocytes to adipocytes, it also stimulated the conversion process once triggering had occurred. This “double-whammy” effect caused a 1,300% increase in fat levels, compared with a 150% increase with insulin alone.

The worldwide obesity epidemic has been primarily explained in terms of poor diet, decreases in exercise, and other lifestyle factors. (I am planning a future series on weight loss, so stay tuned!) However, this research raises the possibility that hormone-disrupting contaminants such as BPA may play a role in regulating weight. BPA triggers and then stimulates two of the key biological mechanisms underlying obesity. It increases the number of fat cells, and it enhances their fat storage.

Health authorities in the US make the claim that the levels of BPA found in most humans are not a risk to human health. However, researchers working in the field have a different view. Ample evidence suggests that BPA can harm lab animals at concentrations below those already occurring in most people.

A report published in Reproductive Toxicology by 38 scientists evaluated the strength of data from more than 700 BPA studies.

The panel concluded that BPA exposure in the womb permanently alters the genes of animals, impairs the function of organs in ways that persist into adulthood, and triggers brain, behavioral, and reproductive effects, including diminished sperm production. Effects deemed likely included a heightened sensitivity to carcinogens, impaired immunity, and diminished insulin sensitivity.

Although the jury is still out on BPA’s ability to cause weight gain in humans, I think the consequences of obesity and the diseases it’s linked to far outweigh the “convenience” of drinking out of plastic water bottles. Of course there are several other reasons not to use plastic water bottles, including the waste they generate and their harmful effect on oceans and sea life.

So do yourself and the planet a favor: get a stainless steel water bottle, and abstain from drinking bottled water! I like the Klean Kanteen brand, but there are many others.

It has also been shown that polycarbonate baby bottles heated by microwave leach BPA into milk fed to infants. So Moms, please don’t heat those bottles in the microwave!

My friend Chris Kresser runs an awesome website called “The Healthy Skeptic” where he debunks all sorts of myths about nutrition and health- just like I do here! You can check out his blog here.