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Could air pollution be making us fat?

Smoke rises from a chimney of a garbage processing plant

The controversial hypothesis proposes that rising levels of CO2 in the atmosphere may be contributing to obesity (Source: Ajay Verma/Reuters)





"What we're doing is trying to be certain that we are not overlooking any very important factors that could be partly responsible for the obesity epidemic," he adds. "I think we should be extremely open-minded about new causes of obesity."

Calories in, calories out




"We need to be open-minded so that we don't in some obsessive fashion continue to pound our heads against the same wall over and over again under the assumption that it is the right path and the only path and that it must make sense, ignoring the fact that we keep doing it and it's not working," says Allison. "I'm not saying that it's calories or this that matters. It's that there are other factors that influence metabolism and body weight."

Weight gain across species







New path towards weight control

If, in addition to an ever-present abundance of soft drinks and fast food, air pollution turns out to be influencing our eating behaviours, it might be possible to make a small dent in the obesity epidemic by lowering ambient CO2 levels or capturing the gas in indoor environments.

At the very least, says Allison, investigating the idea could expose chemical pathways in the brain that might open opportunities for drug treatments. Scepticism is clearly warranted, but he says, the research is worth doing.

"This really interesting novel idea may very well turn out to be wrong, and I would not be shocked at all if it did," says Allison. "But some small fraction of novel ideas turns out to be right. And when we find them, they often open up incredible new vistas."

Tags: climate-change, health, environmental-health, obesity