If you start to delve into the worlds of fitness and nutrition, you can start to come across some confusing term and ideas. One that comes up a lot is BMR (Basal Metabolic Rate), or just references to your metabolism. So, to help you figure out what you should be doing here is the rundown on BMR and metabolism.
What Is Basal Metabolic Rate (BMR)?
BMR is a number that represents how many calories you would burn if you sat around doing absolutely nothing all day. You can think of it as the baseline for the calories you need to eat every day to keep existing. This number is totally independent of what you do all day. Any activity you do adds more calorie burn on top of this basic number.
It helps figure out how much you should be eating on an average day to stay healthy. BMR varies from person to person. There are a lot of factors that affect it, so your number will be different from the other people around you.
Note - Some individuals will talk about your RMR (Resting Metabolic Rate). There is a small difference between BMR and RMR, but for general purposes, you can use the two interchangeably.
How Does It Vary?
Several factors can impact on your BMR. This is why it’s essential to consider your own number rather than just taking a standard one.
As your age increases, your BMR will decrease. As you get older, your body slows down, and your metabolic processes slow. This reduces the number of calories your body needs to keep existing.
Males have higher BMR than females. This is in part to do with the difference in muscle mass, in men and women and in part to do with differences between the way some cell process happen.
Body Mass And Composition
The higher your weight, the lower your BMR tends to be. The composition of your body does matter in this, though. Anyone with a BMI over 30 will be in the lowest categories for BMR. This is in part because the higher levels of body fat insulate the internal organs. This insulation means less energy is needed to maintain your body temperature.
Having a higher proportion of muscle to fat will boost your BMR, as muscle requires more energy to be maintained than fat does.
How To Calculate Your Metabolic Rate
You can use the Harris-Benedict formula to calculate your BMR. It’s a reasonably good estimate but doesn’t take into account, your body composition, only your weight.
Your BMR = (your weight in kg x 10) + (your height in cm x 6.25) - (your age x 5) -161
Your BMR = (your weight in kg x 10) + (your height in cm x 6.25) - (your age x 5) + 5
If you’re not a fan of calculations, you can easily find a calculator online to do it for you.
A more accurate method of calculating your BMR involves using a heart rate monitor. Many fitness accessories, will monitor your heart rate over an extended period and add this to your age, weight and sex data to give a more accurate estimate of your BMR. Not keeping track of your BMR is a common fitness mistake that many people make when first starting out. So it's important you are keeping track of it regularly.
How Many Calories Do I Need?
To figure out the calories you need, you start with you BMR, then consider how active you are on a daily basis. You take your BMR and multiply it by a number based on your activity. You can use the table below to find the number.
Active Days Per Week
0 - 1
1 - 3
3 - 5
6 - 7
Is My Metabolism Slow?
Having a slow metabolism is actually very rare. Symptoms of a slow metabolism include weight gain, extreme fatigue, and low energy. If someone has a truly slow metabolism, they can have difficulty just completing daily tasks. It has been fashionable to blame problems with weight on a slow metabolism. Unfortunately, it’s most often not the case.
In short, the answer to this question is - probably not.
Can I Increase My Metabolic Rate?
Of all the factors that affect your BMR and metabolic rate, the only ones you have control over are your weight and your body composition. So, if you aim to increase your metabolic rate, you can do two things. Firstly you can lose weight. Secondly, you can focus on building more muscle.