Let me preface anything else in this post by clarifying something important. What we are talking about here is a hypothesis—it's not been proven. In fact, it's not even really been tested yet. The studies that will put the hypothesis to the test are currently underway. So please (please, please, please) do not walk away assuming this is a given. It's not. It could very well be completely and utterly wrong. But it's interesting. And it will be in the news. And I want you guys to hear about it in the proper context.
Make sense? Okay, then ...
This idea is (for now) based on "what if" extrapolation rather than data. But it's not totally crazy. We know air pollution affects health in ways would not have been obvious just a few decades ago. For instance, there is a strong, well-documented connection between air pollution and heart disease. In 2009, Aruni Bhatnagar, professor of medicine at the University of Louisville, told me that studies from 250 different metropolitan areas in the United States showed that a spike in air pollution was reliably followed by a spike in cardiac deaths within next 24-48 hours. The people primarily at risk are those who already have underlying heart health problems, but it's not always clear who those people are. We don't yet know exactly how pollution affects the heart—it could well be a cascade of effects that actually starts in the lungs—but we can see that the affect is there.
This new hypothesis, proposed by Arne Astrup, head of the department of obesity and nutrition at the University of Copenhagen, does not come with that kind of supporting evidence. Instead, it's more of an extrapolation.
At Discovery News, Emily Sohn explains why this hypothesis could make sense—and why it's way too early to say whether or not it's actually right.
The idea proposes that breathing in extra CO2 makes blood more acidic, which in turn causes neurons that regulate appetite, sleep and metabolism to fire more frequently. As a result, we might be eating more, sleeping less and gaining more weight, partly as a result of the air we breathe.
...Obesity and its associated health risks have escalated dramatically in the last few decades. And even though just about everyone thinks the reason is obvious -- we are eating too many calories and exercising too little -- research has revealed that obesity is far more complex than that, with multiple genes, metabolic pathways and even gut microbes involved, said obesity researcher David Allison, director of the Nutrition Obesity Research Center at the University of Alabama at Birmingham.