In parallel with the rising obesity rates around the world over the last decades, so too have we seen an environmental trend of global warming. I never stopped to consider that the two might be related – until now.
A thought provoking paper just published by my Danish colleagues suggests that there may be a link between increasing atmospheric carbon dioxide levels (as observed with global warming) and obesity. Breathing in air containing higher carbon dioxide (CO2) level causes the pH of the blood to decrease ever so slightly. The brain is exquisitely sensitive to these small changes, and the activity of neural cells that are involved in appetite regulation are affected. In addition, these decreases in pH may affect neurons that regulate wakefulness, resulting in less sleep, which is a known risk factor for obesity.
Therefore, they hypothesize that these small pH changes in our blood seen with higher CO2 concentrations in the air could lead to an increase in appetite as well as energy storage, and could therefore be one of the many contributors to the high rates of obesity that we currently see.
My colleagues went on to test this theory in a small study of six participants, and found that study participants consumed 6.1% more calories when exposed to higher CO2 concentrations in the air, compared to ambient air. It is noted that this difference was not significant in the study, but a study of a larger size is now needed to see if there is a real difference here.
The obesity endemic, therefore, may be one more important item to add to the list of reasons to put a stop to global warming.