Eat less, move more. That’s been the prevailing weight-loss strategy for years now, but even obesity experts acknowledge that few people who lose weight manage to keep it off.
Meanwhile, in research labs, frogs, mice and zebra fish exposed to minuscule amounts of estrogen replacement drugs, dioxins, bisphenol A and other chemicals are getting fat – very fat.
The phenomenon is so striking that some scientists believe that common chemicals, dubbed obesogens, are messing with our hormonal systems and the natural balance of “calories in, calories out.”
The obesogen theory goes prime time Thursday on the CBC Television series The Nature of Things. In a phone interview, science journalist and filmmaker Bruce Mohun explains the research behind his new documentary, Programmed to be Fat?
We’ve been bombarded with theories about the obesity epidemic, including the idea that antibiotics have disrupted our gut bacteria and made us fat. Why should we pay attention to this one?
This is the one that makes the most sense to the kind of people who study obesity – endocrinologists and toxicologists and obesity experts. They can repeatedly make mice fat by giving them tiny doses of these chemicals.
How widely accepted is the theory that everyday chemicals are making us fat?
Alison Holloway [endocrinologist at McMaster University] put it nicely. She says, ‘Is it plausible that these chemicals are causing obesity? Absolutely. Has it been shown unequivocally? No.’ And that’s why [funding agencies] are starting to dump more and more money into research in this area because they believe that it’s likely that this could be contributing to the obesity epidemic. But they don’t know for sure or how much.
The chemical industry says it has been unable to reproduce the link between obesity and low doses of chemicals in animal studies conducted in response to the independent research. Why?
Well, Bruce Blumberg [biologist at the University of California, Irvine] said to me, ‘Follow the money.’ We did ask industry people to be interviewed – they all refused. If they don’t want to talk about this and they’re [saying] that they’re not getting the same results that Blumberg [and other academic scientists] are getting, well … we decided to go with the people who are unbiased and look at their research.
How might chemicals amplify the effects of bad habits?
Overeating and lack of exercise are a little more obvious – you know, ‘calories in, calories out.’ But how those calories are adjusted and what the body does with those calories, that’s what the endocrine [hormonal] system does. And when you change the endocrine system very, very slightly, it does it a little better – it bumps up our set point.
What about the 2004 documentary Super Size Me? The filmmaker gained 25 pounds in 30 days simply by eating more junk food. Doesn’t this suggest that the Western diet, not chemicals, is the main culprit?
There’s no doubt that if you eat enough, you can make yourself fatter. [Scientists] are not questioning that. They’re saying, Why are babies under six months of age – newborn babies – fatter than normal over a 20- or 30-year period? Why are animals that live in proximity to people – feral animals, farm animals, lab animals – all about 7 or 8 per cent heavier than they were 50 years ago?
Researchers are measuring chemicals in the bodily fluids of volunteers worldwide to see if chemical exposure affects weight. What do you think they’ll find?
A few results have shown a link between higher levels of environmental chemicals in the body and greater propensity to put on weight. [But] nobody is really trumpeting them. [Researchers] feel that they need more people and more studies to really be able to say anything definitively.
But your documentary makes the link sound conclusive.
