How come your body burns 2000 calories a day by existing, but running a mile only burns 100 calories?
In: Biology
Think about all the complexities inside the human body. It needs to be fuelled somehow and it is a gas guzzler.
The 100 calories is for an average 150 lb person, and this is above your normal energy consumption.
If your assumption of 2000 calories a day (BMR) is correct, that’s what you burn just sitting around. So your normal sitting around self burns 83 calories an hour or 13.8 calories in ten minutes.
If you run (jog) a ten minute mile you’ve burned 100 calories above the normal 13.8 calories you would have burned on the couch….so that’s quite a bit more energy burned….a factor of 8.25 times more.
So it’s not really “only” 100 calories….it’s 8.25 your normal energy expenditure.
Many years ago, we had to chase our dinner across the plains and deserts which made our bodies very efficient at running.
Also, not sure where you got that figure from as everyone is different btw, and you’ve not started how fast, incline, fitness etc
>How come your body burns 2000 calories a day by existing, but running a mile only burns 100 calories?
Your body is a bioreactor that constantly transforms stuff into other stuff, pumps stuff from one thing into a different thing, opens and closes valves, sends tons of electrical impulses everywhere and needs to keep itself toasty at a very exact temperature in order for all these other processes to work.
That requires a lot of energy input. About 1500-2000kcal per day.
That’s the **baseline fuel requirement for your body**. Physically moving your *limbs* around (e.g. by exercising) surely factors into it, but just to a very small degree. Accordingly, moving your limbs around *a bit more* does not increase your energetic requirements by a lot. You require far more energy to just *exist*.
A couple of interesting things.
a) The brain is estimated to use around 20% of the calories used (not including additional exercise).
b) The body has to breathe (lungs), circulate blood (heart), run the brain, digest food, filter waste, run the sensory organs, keep the body at optimal temperature, fight potential infections, regrow cells that are lost etc etc. The human body is never NOT doing something just to keep it alive.
c) Humans are rather efficient at 2 legged motion. Even among all the different animal species, humans are nearly at the top of the endurance chart. We’ve evolved to travel very long distances on foot and hence we don’t burn too many calories when jogging or walking. Humans are rather good at it.
Running an eight minute mile takes right minutes.
Burning 2000 calories a day existing takes 24 hours.
If you were to run 8 minute miles for 24 hours at 100 calories per mile, you would burn 18000 calories.
Physical exertion burns a lot of calories, but you can only do it for so long. Base metabolism happens every second that you’re not dead.
Well for one, running a mile might only take you ten minutes or so. If you were running *all day*, you’d burn a lot of energy!
The body has a LOT of stuff going on inside it just keeping you alive. Think about how warm you are. Think about how much energy it would take for you to keep an 80kg sack of meat and saltwater at 37°C all day.
What do you mean “only” 100 for a mile? You’re burning 5% of the “resting” 2000 daily calories in less than 1% of the time. It’s a much faster rate.
Someone let me know if my logic or math is off, but…
* If I’m burning 2000 calories per day doing nothing, then that’s 2000 calories / 24 hours = 83.333 calories/hour for sitting on my ass, typing this out.
* If I run a mile, that’s 100 calories for about 7 minutes, 30 seconds. I’m using [this resource](https://runninglevel.com/running-times/1-mile-times), which averages times for males and females for a range of ages and skill levels.
* So if I’m running a 7:30 mile, then I can run 8 miles in an hour (60 minutes divided by 7.5 minutes/mile = 8 miles).
* To compare my calories burned per hour, running 8 miles an hour x 100 calories/hour = 800 calories/hour, or nearly 10x what I’d burn in the same hour, just existing
* Or in other words, running for 2.5 hours (2000 calories, divided by 800 calories/hour) would burn a day’s worth of “just existing” calories.
* No it’s not 5YO math, but that’s about as simple as I can get it.
Long story short: when you run, 20 minutes is an eternity. But when you sleep, 6 hours is short.
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