Welcome to my science based guide on how many calories your muscles actually burn.
Maybe you've heard that with more muscle mass, you'll be able to burn off more calories (even if you sleep on the couch all day).
Maybe you've even heard that each pound of muscle you put on will burn off 50 extra calories every single day.
In any case, read this guide all the way through and I promise you'll have your answers.
This guide is based on some pretty awesome research[1] that took a really close look at how our bodies burn calories.
More precisely, the scientists figured out how many calories are burned away by our vital organs, our muscles, and even our body fat.
Before we dive in, here's a quick overview of everything I've covered in this guide:
How many calories per day do you burn doing nothing?
The number of "resting calories" you burn off per day is also known as your resting metabolic rate.
(These are the calories your body will burn off, even if you literally lie in bed all day.)
Figuring out how many resting calories per day you actually burn off can be a bit tricky.
For example, the resting metabolic rates of people in the study fell anywhere between 1200 and 2100 calories per day.
The number of resting calories they burned off in a day, depended on their age, sex, height, weight, and some other factors.
So, let's take a look at some of the options you have, if you're interested in figuring out your own metabolic rate.
Calculate your own resting metabolic rate with this
As it turns out, you can use many different methods to calculate your own resting metabolic rate.
And while all of them will only give you an estimate, some of them can give you pretty accurate results.
According to science[1], the formula that is the closest to real life results, is the so called "Mifflin-St Jeor equation".
But instead of boring you with math, and leaving you no other choice but to calculate your own resting metabolic rate manually, I've taken the time to create a convenient resting metabolic rate calculator for you.
Simply enter your own information, and you'll find out how many calories you're burning off every day (even if you lie in bed all day).
How precise is my resting metabolic rate calculator?
Research[1] says, my calculator will fall within 10% of your actual resting metabolic rate.
So, if my calculator comes up with, let's say, 2000 resting calories per day, you could actually be burning off as many as 2200 calories a day, or as few as 1800 calories a day.
If you wanted to measure your resting metabolic rate more precisely, you'd have to get it done at a specialized facility.
(And pay for it, of course.)
But, overall, the method my calculator uses, is currently the most precise "rule of thumb" method out there.
Which organ in your body burns the most calories?
Ok, now that you have a good idea on how many calories your body is burning off during rest, let's take a closer look at how your internal calorie burning furnace works.
Here are some of the greatest calorie burners in your body:
- Your internal organs (brain, liver, heart and kidneys) are responsible for almost 60% of your resting metabolic rate. If you burn off 2000 calories per day, your internal organs singlehandedly burn off around 1200 of those calories.
- Your muscles burn off only about 22% of daily resting calories. If you don't put your muscles to work, they'll only burn off around 400 out of 2000 calories per day.
- Surprisingly, even your body fat body helps out a little, even though it only contributes around 4% to your resting metabolic rate. But still, burning off "just" 80 out of 2000 is better than nothing.
- The remaining daily resting calories (about 14%) are burned away by the so called "residual" body mass. That mass includes all the tissues in your body that don't fall within the first three categories.
So, (by far) the most calories get burned off by your vital organs and NOT your muscles.
How many calories does 1 pound / 1 kilogram of muscle burn?
Let's do some simple math:
The people in the calorie burning study had approximately 63 pounds (29 kilograms) of muscle mass on average.
On average, they also burned off around 1,700 resting calories per day.
Because muscles contributed only about 22% of total calories burned, this means they burned off around 350-400 calories on average.
All of this comes down to:
Each pound of muscle burns off around 6 calories per day and each kilogram of muscle burns off around 13 calories per day.
So there you have it, a far cry from 50 calories per day, but still nothing to be frowned upon.
How many calories does 1 pound / 1 kilogram of body fat burn?
Just for the sake of completeness, let's also calculate how many calories your body fat is actually burning off:
The people in the study carried around about 30 pounds (14 kilograms) of body fat on average.
If we follow the same logic, that the people in the study burned off 1700 calories per day on average (while their body fat burned off 4% of those calories), we get:
Each pound of body fat burns off a little over 2 calories per day and each kilogram of body fat burns off around 5 calories per day.
The good news is, our body fat isn't some totally passive tissue stuck on our bodies, but it actually helps us burn off some calories.
The bad news is, we're trying real hard to burn off those calories to get rid of that stubborn body fat in the first place.
Once it's finally gone, it won't really be able to help us burn off any extra calories anymore.
Is building muscle to burn off more calories really worth it?
Well, if you hit the gym real hard and put on 10 pounds (4.5 kilograms) of muscle, you'll "only" be burning off around 60 extra calories per day.
If you ever make it to putting on extra 20 pounds (9 kilograms) of muscle, you will get to burn off 120 extra resting calories a day.
Now, before you rush out to spend your money on a gym membership, let me be a bit blunt:
Not a whole lot of people ever put on extra 20 pounds of muscle in their lives.
But I'm definitely not saying that you shouldn't even try to put on more muscle.
I'm only saying, that in spite of the many benefits of "bulking up", you shouldn't expect any calorie burning miracles from it.
Summary (actionable takeaways)
As you saw, science has successfully put another weight loss myth to rest.
The sad truth is, your muscles can't burn off anywhere close to 50 calories per pound of muscle mass.
Unless you actually put those muscles to work, each pound of your muscles will only burn off around 6 extra calories per day.
By far the biggest calorie burners in your body are actually your vital organs (they singlehandedly take care of 60% of your resting metabolic rate).
Not even your body fat just sits idle, though a pound of body fat will only burn off 2 extra resting calories a day.
Written by Rok Sprogar, CNC, WLS
Rok Sprogar is a NASM Certified Nutrition Coach (NASM-CNC) and a NASM Certified Weight Loss Specialist (NASM-WLS) who has been contributing highly actionable and science-based content to Leanhigh.