Daily Smart Fact #32: Why You’re Fattest at Night and Skinniest in the Morning

Takeaway: You lose more than a pound every night from breathing.  That’s because you breathe in oxygen (O2) and breathe out carbon dioxide (CO2 – two oxygen atoms plus a carbon atom), “so there’s an extra carbon atom leaving in every round trip.”

I like weighing myself.  Call it my own personal body experiment, but I enjoy seeing the fluctuations of my weight throughout the day – in the morning, after I eat, before/after I go to the restroom, right at night.  It might sound obsessive, but I’m not trying to lose weight – it’s just fascinating to observe the fundamentals of input/output on your own body. Eat a POUND of cheese?  Yeah, you’ve just gained an immediate pound.  Drink 24 oz of water?  Yeah, you just gained 24 oz. on that scale.

Anyway, I stumbled upon a neat article that my friend (hi Li!) posted on Facebook and found it intriguing: Every Night You Lose More Than a Pound While You’re Asleep (For the Oddest Reason).  Basically, this guy records himself over a couple of days weighing himself at night and then again in the morning, wearing the same clothes.  He interviews people and eats hamburgers and goes to the bathroom, fun stuff.  Not the most rigorous scientific experiment.  But his finding at the end is that, just breathing at night, thousands of breaths over a typical 8-hour sleep, results in us losing about a pound or more just from the extra carbon that gets expelled.