Born to be fat

Does prenatal exposure to chemicals called ‘obesogens’ help explain the epidemic of obesity?

Born to be fat

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Why are babies growing fatter and more quickly these days? This question has been puzzling Michelle A. Mendez, an epidemiologist at the Centre for Research in Environmental Epidemiology in Barcelona. “What could make them less active or eat more at such early stages of life?” she ponders over the phone from her office. “Is it just that parents are suddenly stuffing their children with food or is something else increasing their susceptibility to gaining weight?”

There’s been a dramatic increase in obesity in all age groups all over the world, but especially among kids. Rates of overweight European schoolchildren, for example, shot up from nine per cent in the mid-1970s to 24 per cent in 2000. In Canada, more than a quarter of children aged 2 to 17 years are overweight or obese. So Mendez—like other scientists who believe there are other causes for the obesity epidemic besides too many french fries—began to explore potential triggers for the tipping scales. In particular, she looked at whether early-life exposure to small amounts of chemicals in our environment make babies fat, possibly predisposing them to weight gain throughout life.

Using data from 518 pregnant Spanish women, Mendez and other researchers measured chemicals in the moms’ blood, such as DDE (a by-product of the now widely banned pesticide DDT, which lingers in the environment decades later, and is still found in small amounts in many foods such as meat, dairy and fish), to see if they correlated with fatter and faster-growing babies. The result: children of normal-weight mothers who had elevated levels of DDE in their systems were twice as likely to grow quickly in their first six months, and have a high body mass index (BMI) at 14 months. And, says Mendez, “Rapid early growth is associated with obesity in childhood and adulthood.”

The study, published in the journal Environmental Health Perspectives, is the latest addition to the mounting body of evidence that endocrine disruptors—chemicals that can mimic and interfere with the body’s hormones—may have adverse effects on human and animal health, among other things, triggering obesity. Known colloquially as “obesogens,” these pollutants, like DDE, are believed to alter or block the activity of natural female  and male sex hormones, causing fat to store more efficiently, and spurring the creation of fat cells where cartilage or bone would have been. “In the last five years or so,” says Mendez, “we’ve been realizing there may be more to the obesity epidemic than just bad diet and not enough exercise.”

Studies on animals have shown that exposure around the time of birth to even trace amounts of everyday chemicals can predispose subjects to weight gain throughout life. Perfluorooctanoic acid, found in non-stick pans, microwave popcorn bags and pizza boxes, has been associated with obesity in female mice. Bisphenol A, used in plastics and recently declared a toxic chemical in Canada, is linked to obesity in rats. Similarly, triclosan, an ingredient in antibacterial hand soaps, dishwashing detergents and other body care products, has been correlated to faster growth in frogs. Caren Helbing, a researcher at the University of Victoria who worked on the triclosan study, notes, “It’s critical to realize that some of the manufactured chemicals that have been important for protecting people, like flame retardants, were designed without thinking about how they would change the way hormones in humans work.”

The grandfather of the obesogen studies is Bruce Blumberg, a cell biologist at the University of California, Irvine. He coined the term “obesogen,” and has focused on mice and how they are affected by tributyltin (TBT), a pesticide added to paint used on ships to prevent the growth of marine organisms like barnacles and algae, which enters underwater environments and ends up in our seafood. “We found that if we treat pregnant mice with tributyltin, the pups in their womb will be predisposed to getting fat later in life,” Blumberg says. “They make more fat cells, and that appears to lead them to be heavier.”

These changes in animals are thought to be indicative of changes in humans, and the idea of obesogens as the new weight threat has caught on. Some folks, like the authors of a 2009 book The New American Diet, are even trying to capitalize on the notion that you can undo “the obesogen effect” through a special diet. But Blumberg says more empirical data is needed to understand how these chemicals work on humans at all stages in life, and whether the effects of early exposure can be reversed.

In the meantime, most scientists working on endocrine disruptors agree that staying away from chemicals, wherever possible, is a good idea. That means opting for glass or stainless steel instead of plastic, avoiding scented and anti-bacterial products, seeking out cosmetics and body products with fewer ingredients, and, perhaps, eating organic foods and wild fish instead of farmed varieties, which contain more pesticides. “Obesity correlates with lots of things, not just plastic,” Blumberg says, “but if it were as easy as just balancing your caloric chequebook, would anyone be obese?”


Born to be fat

  1. Okay, so, clearly, this Blumberg guy ain't stupid. So why would he go and say something as stupid as this:

    "but if it were as easy as just balancing your caloric chequebook, would anyone be obese?"

    Of course, the answer is, "Yes, absolutely!" because lots of people still value their tasty, high-calorie foods over their long-term health (or even their vanity), and/or value sedentary activities (such as reading, video games, TV, and needlepoint) over more physically active diversions. But this guy says it as if he fully expects the answer to be, "No way!"

    Proof that even smart people can hold stupid ideas and say stupid things.

  2. There may be something to this, but I suspect the real reason obesity is increasing is because our kids are less active today than they were in previous decades. Part of the reason is because many families don't feel safe letting their kids play unsupervised in parks or other places – every trip outside must be supervised, leading to less trips outside. The other part of it is the lure of video games, the internet and other sedentary activities that are in many cases cheaper than organized sports, and are certainly less effort for parents. Many of us now live in environments where you have to constantly work at finding ways to keep your kids physically active – and that can easily fall to the bottom of a busy parent's list.

    • Here, here. Well said.

    • Bullsit.

  3. @DirtyOldTown – Which is why we all need to use the Wii or Kinect or the PS Move!!

  4. While I'll be the last person to be comfortable with the reckless addition of more potentially harmful chemicals to the environment or to argue that there may not be a link between existing chemicals and adverse health effects, it's all too easy to lay the blame for obesity on the "chemical bogyman."

    As mentioned by "DirtyOldTown" I think the main causes of childhood obesity are much more mundane. Looking at how my kids spend their time compared to how I spent my time as a kid I would say the main culprits are primarily much easier access to high calorie, less nutritious food and much lower levels of activity for a variety of reasons.

  5. Calories in calories out. Full Stop. The BS and baffle gab is just incredible. Kids are fat because they are stuffing their pie holes far too much with crap and sitting on the couch text messaging. If you want proof all I have to do is look at our local paper(Herald) which publishes anniversary pics of couples married in the 50's & 60's. Every single one of those pics show rail thin people. No fatties. On the same page are current engagement pics. Virtually everyone is fat. Females with upper arms exploding out of sleeveless tops, males with jowls and beer guts. Sadly it's now gotten to the point where grad pics show 18 year olds exploding out of prom dresses. Meanwhile phoney scientists rationalize this health crisis. Sad really.

    • Uh, how does looking at people that married in the 50's and 60's (who were not exposed to obesogens) discredit this guy's theory? If fatter people are more likely to die young and less likely to get married, wouldn't that suggest looking at people celebrating their 50th/60th anniversary is a monumentally bad means of analysis. And anyway, your age-obesity hypothesis is wrong: old people are fatter than young people. http://www.statcan.gc.ca/pub/82-620-m/2005001/c-g….

      Obviously obesity has increased over time – that is a statistical fact. Lifestyle choices surely have to do with this, but plenty of people that make healthy lifestyle choices still have problems (its a big problem that probably has diverse causes). Calories in calories out is overly simplistic, and doesn't account for the fact that different people store/process calories differently.

      Even in the same person, calories in calories out works differently. For instance, if you didn't eat for 6 days, but then ate 12,000 calories, you would probably gain weight despite averaging 2000 calories a day, because your body metabolizes things differently when in starvation mode. Alternately, any pregnant woman will tell you that hormones impact their tendency to gain weight from a given amount of food (not to mention their eating habits).

      I'm not disputing that many people make bad choices (I am speaking from the perspective of a thin person that often makes bad choices), but from an epidemiology perspective it is surely worth understanding why people make bad choices, and how to help them make good ones and even how to reduce the impact of bad choices (if you could invent a good zero calorie beer – why NOT do it). Whether you like it or not, texting, unhealthy food, and jobs requiring long periods of low activity levels are probably here to stay – how do we make the most of the world we've got?

  6. Maybe this is true, who really knows..But the way I see it is parents are too damn lazy to make their kids healthy meals, instead they opt for the quick meal (process foods) which are loaded full of fat and calories then proceed to let them sit on their butts in front of TV with a bag of chips and a bottle of pop..Its the parents who need to smarten the hell up with their obese children and stop balming everyone else for the way their kids look.

  7. "Perfluorooctanoic acid, found in non-stick pans, microwave popcorn bags and pizza boxes, has been associated with obesity in female mice. "
    Perfluorooctanoic acid, huh? Sure, but not the salty popcorn, greasy pizza and other fat goodies cooked in the non-stick pan?
    I don't doubt that chemicals are wreaking havoc on our systems, but some smarter food choices are really an obvious answer.

    • I agree regarding bad choices, but the proportion of fat people consume has decreased since the 1970s as obesity has skyrocketed. We eat less red meat and more poultry (and pork has essentially become white meat). In many respects our low fat obsession is part of the problem. Refined corn syrup started to replace fat – providing calories without making people feel full.

  8. About 5 years ago I started working in a factory that had toluenes, moca, and some other nasty chemicals. Even though I worked in the office and would be in the factory for no more than 1 hour per day, I mysteriously put on 20 lbs. I up my exercise program and ate especially well. I would lose 5 lbs and would feel like I had the flu the whole time I was losing weight. I continued to hold the 20 lbs in spite of eating very well (no sugar, no booze, no fast food, no white products)

    I left that factory last spring and lost 10 lbs the first 2 weeks without effort. Then I started detoxing and felt like I had a continuous flu for about 1 month and lost the next 10 lbs with no effort. Since then I have read Dr. Walter Crinnion's work on chemicals and weight and found out this is very typical. One thing about the factory is the women put on 20 lbs immediately and all the men who worked in the factory were skinny!!! My children are of normal weight, but again no pop, no snack foods, no fast foods in my house.

    I think there needs to be more work done in this area.

  9. Unfortunately, this article demonstrates another example of how media misrepresents science. Reading the original article, available here, http://ehp03.niehs.nih.gov/article/info%3Adoi%2F1… you will notice that the authors found significant results ONLY after stratifying by weight of the mother. This did not seem to be part of the study protocol and probably was done as an after-thought. Some may say "so what"?, but the reality is you can find statistical significance merely by increasing the number of analysis trials. So if you keep doing analysis, chances are you will find statistical significance, but that can be merely by "chance". This is why authors should stick to the original protocol and only do analysis as was decided BEFORE initiating data collection. This is done to avoid "data fishing".

    Also, the reference to all these animal studies should also be treated with caution. This is simply because humans are very different in the way they process chemicals from animals. Also, these animal studies often use lethal doses of chemicals when making comparisons. Humans are often exposed to much lower levels.

    I am not arguing that we should not be aware of the risks of chemicals. However, media should spend more time ensuring that the interpretation of a study is done properly to avoid making unsubstantiated claims.

  10. Its an obvious chemical warfare. It always is.

  11. It is scary to think about how the environment can have such a big impact on us and even the kids that haven't been born yet, and there are still a lot of things have yet to be discovered.

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  12. Time to cut out the junk food I think

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