What Is Your Metabolism?

You've probably heard the word "metabolism," especially as it relates to weight loss or gain. But what is your metabolism, what does it do, and do you have any control over it? Get-Fit Guy Brock Armstrong explains.

Brock Armstrong
7-minute read
Episode #424
The word metabolism in the dictionary

Scientifically speaking, "metabolism" is a term that describes all the chemical reactions involved in being a living organism. And while it is true that metabolism is linked to body weight, a slow metabolism is rarely the root cause of excess weight gain.

While there are health conditions that slow the metabolism such as Cushing's Syndrome or an underactive thyroid gland (hypothyroidism), those cases are quite rare. So while it may be tempting to blame your metabolism for weight gain, it is a natural process and your body has many mechanisms that regulate it to meet your individual needs.

Our BMR is best defined as the average amount of calories we expend while simply living our best lives.

Most often, when we talk about metabolism, we are actually talking about what is known as our basal metabolic rate (BMR). And our BMR is better defined as the average amount of calories we expend while simply living our best lives.

Basal Metabolic Rate

The most accurate way to find out your basal metabolic rate is to have it measured in a lab. But you also can calculate an approximation of your metabolic rate using an online calculator. Or you can also use the Harris-Benedict Equation:

  • Men:  BMR = 88.362 + (13.397 x weight in kg) + (4.799 x height in cm) - (5.677 x age in years)
  • Women: BMR = 447.593 + (9.247 x weight in kg) + (3.098 x height in cm) - (4.330 x age in years)

Then, after you have your approximate BMR, you can find out your total metabolic rate. But as I will explain shortly, your total metabolism (metabolic rate) is a combination of your BMR and other myriad metabolic processes.

What Affects Your Metabolism?

Metabolism is mostly affected by what your body (specifically your muscles) are doing at rest - not just the small percentage of the day when you are exercising. For the most part, it is our muscles' resting metabolism that makes up the greatest portion of BMR.

Metabolism is also the process by which the body converts food into energy. During this biochemical process, the calories in our food are combined with oxygen to set free the energy that we need to stay alive.

Even when we are asleep, our bodies need this energy to do things like breathe, circulate blood, regulate hormone levels, and grow and repair. The amount of energy our body uses to carry out these functions contributes to our basal metabolic rate.

When you exercise, play a sport, or otherwise raise your heart rate, your metabolism is temporarily affected but it is the metabolic activity of your muscle mass at rest that defines it. So, if you want to have the healthiest amount of muscle mass in proportion to your skeletal mass (which is my fancy way of avoiding the term BMI), you need to focus on increasing the activity of the electrical channels in your muscle system.

What is the best way to do that, you ask? Well, it’s not a scientifically devised workout that I will sell to you for $59.99. It is in fact simply moving your body more, and more often.

The factor which messes with our body’s health the most is the amount of time we spend having zero electricity flowing through our muscles.


About the Author

Brock Armstrong

Brock Armstrong is a certified AFLCA Group Fitness Leader with a designation in Portable Equipment, NCCP and CAC Triathlon Coach, and a TnT certified run coach. He is also on the board of advisors for the Primal Health Coach Institute and a guest faculty member of the Human Potential Institute. Do you have a fitness question? Leave a message on the Get-Fit Guy listener line. Your question could be featured on the show.