I believe in a lot of kooky theories. Not kooky meaning crazy; I wouldn’t believe them if I didn’t think they were true. But kooky in the sense that they’re not mainstream, and I wouldn’t be surprised if they were disproven. But until then, I think they make a lot of sense and explain quite a bit.
One of my most recent theories is that rising CO2 levels in the atmosphere causes weight gain. This is based on a single study from an obscure journal that exposed 6 men to higher CO2 levels for seven hours and observed that they ate far more afterwards. Pretty flimsy. But the study does explain a mechanism of how it might be possible, and also notes that the area of the U.S. that has the highest CO2 levels also has the highest rates of obesity.
It also explains something that I find otherwise inexplicable. It’s well known that people around the world have gotten fatter in the last 20 years. What doesn’t get a ton of press is that animals have also gotten fatter over the same time period. This includes pets, lab animals, even those in the wild. Pets and wild animals living near humans getting fatter can be explained by the same changes in food that might have made us fatter. But lab animals who have been fed the same diet? Other wild animals? Doesn’t make sense. Someone theorized that lab rats are being housed more densely now and thus they have less room to exercise, and that’s why they’re getting fatter. That seems like a stretch.
A more straightforward explanation to me is that there’s something environmental going on, and rising CO2 levels seems as likely as anything else. Even if it’s not, there’s something weird going on making everything on the planet fatter.