“Does muscle burn fat and does building muscle increase the body’s metabolic rate?”
This is a question we got from a few of our readers in the last couple of weeks, so we thought we’d write a short article to help shed some light on the topic.
Before you keep reading, just know that the answer is probably not what you think it is, so be prepared!
So does muscle burn fat and increase metabolism? Let’s find out!
Metabolism: what is it, really?
First things first, what exactly is “metabolism”?
Metabolism comes from the Greek word “metabolē”, which means “change” and is, technically, the sum of all anabolic and catabolic processes happening in your body.
- Anabolic processes are those where larger molecules are constructed from smaller ones. For example, building muscle tissue (i.e. proteins) from amino acids is an anabolic process.
- Catabolic processes are those where larger molecules are broken down into smaller ones. For example, breaking down muscle tissue (i.e. proteins) into amino acids is a catabolic process.
Put simply, your body is in a constant state of change, where energy is used to build up and to break down molecules. This constant state of change is called “metabolism”.
Components of energy expenditure
Admittedly, the above explanation of “metabolism” isn’t very helpful nor does it clear things up.
In reality, when most people talk about “metabolism”, they are referring to the body’s metabolic rate or Resting Metabolic Rate (RMR), which is one of the following four components of energy expenditure:
- Resting Metabolic Rate (RMR). This is the amount of energy required to maintain the body’s main functions at rest and is what people usually refer to as “metabolism”.
- Thermic Effect of Food (TEF). This is the number of calories burned during the digestion and absorption process of the food we eat.
- Thermic Effect of Activity (TEA). This is the energy expended during physical activity in the form of exercise.
- Non-Exercise Activity Thermogenesis (NEAT). This is the amount of energy expended during everything else that doesn’t fall into the above categories and includes things like fidgeting, maintaining posture and shivering when it’s cold.
So now that we’ve defined what exactly we are talking about, we can begin to answer our original question!
Does muscle burn fat and increase RMR?
You may have heard before that muscle increases our Resting Metabolic Rate and that, consequently, building muscle means that our body will be burning more calories and fat at rest.
This is absolutely 100% true!
You may have also heard that 1 pound of muscle burns an extra 50-100 calories per day at rest, while body fat is completely metabolically inactive.
Well, this is actually quite far from the truth.
You see, according to scientific research, the number of calories burned by 1 pound of muscle at rest is closer to 6 calories per day; not 50 and certainly not 100. This means that, if for example, you manage to gain 10 pounds of muscle, your Resting Metabolic Rate will increase by only around 60 calories per day.
With regards to body fat, it’s also not true that it is completely metabolically inactive, as 1 pound of body fat burns around 2 calories per day at rest.
For comparison, 1 pound of heart or kidneys burns around 200 calories per day at rest, 1 pound of brain burns around 110, while 1 pound of liver burns around 90 calories per day.
Training to build muscle increases RMR
Although more muscle per se doesn’t increase resting metabolic rate much, scientific research suggests that training for muscle growth (i.e. high volume, high-intensity training) significantly raises the body’s Resting Metabolic Rate for several hours after the exercise bout.
In fact, a study published in the European Journal of Applied Physiology found that heavy resistance training significantly raised the oxygen consumption of seven young men until about 38 hours after exercise!
This elevation in oxygen consumption, called EPOC (Excess Post-Exercise Oxygen Consumption) is likely because of an increase in the activation of the sympathetic nervous system, a rise in lipid metabolism (i.e. fat burning), increased phosphagen (ATP/CP) and glycogen resynthesis, and an increase in the rate of lactate removal.
Simply put, when you lift heavy weights, you burn more fat and your metabolism increases in the hours that follow because your body is trying to recover!
Conclusions and recommendations
So does muscle burn fat and increase metabolism?
Well, kind of, but not exactly.
At rest and outside the recovery process, muscle actually contributes very little to the body’s metabolic rate, pound for pound. However, high volume, heavy resistance training (which is what builds muscle) significantly increases fat burning and the body’s Resting Metabolic Rate in the hours and days that follow.
Is resistance training really just about burning fat and increasing metabolism, though, or are we missing the forest for the trees?
Well, in our opinion, there are hugely more important reasons why you should be lifting weights and trying to build muscle. This is a topic for another article, however, so we’ll just leave it at that.
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