Carbon footprints are a big talking point at the moment - they're your personal contribution to greenhouse gases, usually in terms of carbon dioxide, or CO2 emissions.
The latest research out of Denmark suggests our footprints might be getting deeper as well as larger, with the news that CO2 emissions could be making us all fatter.
If that sounds like a load of hot air we'd forgive you the skepticism, but Science Nordic reveals that the results of a 22-year study have concluded not just that obesity has increased, but that thinner people are proportionally fatter than they were 22 years ago too. The cause of this is, apparently, increased CO2 levels.
The theory is due to the hormones in the brain responsible for "wakefulness", or the amount of time we spend awake. CO2 levels can affect these hormones, leading us to go to bed later, which affects our metabolism making it easier for us to gain weight.
It also makes us eat. Breathing in increased CO2 makes our blood more acidic, affecting our brain patterns, making us want to eat more.
If that still sounds perculiar, consider that a study conducted in 2010 has also seen the same effects in different species of animal - so it's not just the proliferation of fast food restaurants leading to humans piling on the pounds.
Of course, wait gain isn't some depressing inevitability, and eating healthily and doing exercise can mitigate the effects of packing away hamburgers and guzzling cola all day long.
And if you find yourself constantly buying larger pants, we don't think you can blame it entirely on increased levels of CO2.
The research is still ongoing, and as befits the nature of a scientific hypothesis, the research is open to the scientific community to refine or disprove
So what does all this tell us?
Probably to walk more. After all, if you're driving everywhere you're not only not getting any exercise, but you're contributing to the CO2 output that could be making you even fatter...