Have you ever jumped on the scale the first thing in the morning and loved the number you saw? Only to weigh yourself again later that day and noticed an increase? It’s important not to let these daily fluctuations impact your body image attitude.
We all know that you body weight can fluctuate 2-5 lbs over the course of the day because of things going in and things going out. But have you ever wondered why?
You’re probably thinking water. I’m losing water weight overnight and I’m not putting any food or fluid in. Which is true but it’s only part of the story.
I recently listened to a RadioLab podcast where they asked this very question. Brace yourself, I’m about to throw some science at you as I summarize their findings.
Overnight, your body burns about 77 calories per hour. On a cellular level, your body is breaking down carbon bonds (molecules within the food you eat) which contain a certain amount of energy (measured in calories). In order to fuel this process, we need in inhale oxygen (O2) and we expel carbon dioxide (CO2) as a waste product. So for every 2 oxygen atoms you breathe out you expel two oxygen atoms along with one carbon atom.
So that imbalance sets up the weight loss equation. Each atom weighs essentially nothing until you think about how many molecules are in each breath. This podcast estimated that we breathe out ten billion trillion atoms in every breath! And with approxmately 16 breaths an hour for 8 hours. The potential weight loss through your breath alone really adds up.
That’s not the end of the story though. The other part has to do with water. Our breath isn’t just oxygen and carbon dioxide. We breathe out water vapor as well. The air we breathe is anywhere between 40-60% relative humidity (a comfortable sleeping environment). Our bodies humidifies and warms the air as we breathe in. The resulting out breath is approximately 90 degrees and 100% humidity. The increase from 40% to 100% requires water coming from our bodies. Hence the water loss.
Bet you never thought so much about your breath!
Here’s the video from the RadioLab podcast. But a warning, you have to think in metric as this researcher is from Australia 😉