Slow Vs Fast Metabolism – Does It Matter For Your Fat Loss Goals?

Slow Vs Fast Metabolism – Does It Matter For Your Fat Loss Goals?

I don’t think anything is more heavily debated in the health and fitness industry than how your metabolism affects your body shape. 

From obese people claiming there’s nothing they can do due to genetics, to bodybuilders misunderstanding the processes to effectively plan a cutting phase, there just seems to be too much confusion.

Saying that you have a fast or slow metabolism completely oversimplifies quite a complex process of breaking down, absorbing, and using nutrients. A process that is directly influenced by many factors that can be changed. 

Let’s take a deeper dive into what actually happens. 

What Does Your Metabolism Actually Do?

There are two key factors in what we refer to as metabolism, and just saying that your metabolism is slow or fast doesn’t really paint the full picture. It’s much more a case that the balance of these processes dictates how much fat you can actually burn.


Anabolism is the process of digestion and absorption. As you consume food, your stomach and bowels are in charge of breaking down the food and then absorbing the nutrients. 

This process itself is very heavily reliant on energy, meaning that a lot of the calories you take in with your food are actually needed just to be able to absorb the nutrients in the first place. 

Essentially, anabolism is the process in charge of making nutrients available for energy production in your body.


As carbs, fat, and protein enter your system, it’s catabolic processes that take over in order to release the energy contained in them. This energy is then used to fuel the brain, muscles, organs, and any kind of cell functionality.

In addition to processing nutrients from food, catabolism is also capable of releasing energy from stored glycogen and fat. It does this when not enough energy is taken in through anabolism. 

Basal Metabolism

Even when you’re at rest, your body will use up energy for things like breathing, blood circulation, repairing cells, digestion, and brain functionality. Up to 70% of your entire energy output will go on these resting processes, and it’s these that most heavily impact your fat storage.

Ultimately, it’s not how fast or slow these processes work, but what kind of balance they are in. 

And this balance is influenced by several things. 

What Influences Your Metabolism

I’ll get to some common myths about metabolic rate in a moment, but one thing you have to keep in mind is that your metabolism is constantly changing and many outside factors have a direct influence on it. 

Age And Gender

Men have a naturally higher muscle mass than women, which means that they naturally burn more calories to keep those muscles functioning. Similarly, with age, your muscle mass will naturally decrease, resulting in a lower basal metabolic rate.

What also comes into the equation here is hormonal balances and thyroid function. Men and women of different ages will have very different dominant hormones, and the thyroid gland will naturally adapt to aging. 

As a result, your muscle mass and appetite will significantly fluctuate, which can result in a shift in metabolic rates.

Muscle Mass

This is a very significant factor that most people completely ignore. As you grow bigger muscles, your basal metabolic rate will increase as well.

This means that increased muscle size means that you can actually eat more without getting fat.

So, when you hear someone complain about that 20-year old friend who can eat burgers every day and still appear ripped, it has more to do with the fact that they are male, young, and have the muscle mass to sustain higher calorie consumption. 


The saying goes: You are what you eat. 

And while that might sound a bit simplistic, there is a lot of truth in it. But it’s more the case that your metabolism is influenced by how much you eat, especially when it comes to refined carbs.

These types of carbs are very easy to digest and ultimately cause blood sugar spikes. The excess is then stored as fat cells if your net calorie intake is positive. 


Exercise is one of the best regulators of your metabolism. The more physically active you are, the more your body will utilize catabolic processes. These first target blood glucose, then glycogen, and then fat.

So, the more you’re able to use up the readily available energy sources, the more likely your body will target fat cells.

Whether that fat will remain gone is ultimately dependent on that all-important net-calorie balance every day and week. There’s no point having a net negative on your exercise days, and then a net positive on your rest days. 

And that’s where most people go wrong when it comes to cutting. 

Common Metabolism Myths

Now that we’ve clarified what your metabolism is and how it’s influenced by outside factors, I also want to highlight a few misconceptions and myths that are all too common.

1 – It’s All Genetics

There is a school of thought in the public that your metabolism is fully dictated by your genetics. While there is a partial truth to this, in that every cell and function in our bodies is indeed the result of a genetic code, it’s not quite that straightforward.

Yes, your genes create the organs that control your metabolism.

But we are all born with the ability to absorb and process nutrients, and our genetics don’t directly dictate how much energy we’re able to process. 

This happens in a much more indirect way.

For example, how fast your muscles can repair and build new fibers is controlled by your genes. Some people are fortunate enough to find it much easier to bulk up faster. 

And as you read above, the more muscle you build, the higher your basal metabolic rate is, the more energy you’ll be using while resting. 

Essentially, your genes influence your muscle mass which directly impacts how much energy you can consume before you start piling on the pounds.

2 – It Cannot Be Changed

This is usually a statement you hear from quitters who simply cannot maintain the necessary levels of activity and commitment to dieting. Your metabolism absolutely can be changed by your behavior. 

If you eat less and train more, then the only way you can fuel the activity is with stored fat reserves. Most people I know that failed to achieve their cutting goals were either not dedicated enough to hard work, or they failed to adjust their diets. 

Blaming some made-up concept that you won’t find in any physiology textbook is just a way to mask a failure to commit.

3 – Eating More Or Less Often

I’ve heard this a lot as well. Basically, the idea is that you can kick your metabolism into overdrive by either eating the same amount over 2 meals or 7 meals. 

In both of these cases, the false idea is that both anabolic and catabolic rates can be influenced by the number of times you eat. 

In reality, digestion and absorption of nutrients takes quite some time, and in many cases several days. The concept completely ignores that anabolic and catabolic processes work in unison and that it’s the balance between these processes that counts. 

Eating different volumes in different stages has an impact on anabolic processes, which is only one piece of the puzzle. 


Over the years, the entire debate about slow and fast metabolic rates and how easy or difficult it is to get rid of fat reserves has very much ignored a much more important underlying factor. 

You’ve learned that your metabolism is not one single process and that the balance of anabolism and catabolism is what ultimately dictates whether you can burn some extra fat reserves.

If you want to cut some fat, then you have to eat less and do less intense exercises.