You may have heard others talk about their fast or slow metabolism, but you may not understand how to calculate your basal metabolic rate or what this means for you when it comes to your health and fitness goals. Basal metabolic rate (BMR) is the energy that your body expends while you simply rest. In terms of calories, it’s the minimum number of calories that the body burns while at rest. This energy that is released as you rest is enough energy for your body to keep going and keep the organs going strong.
It can benefit you to learn how BMR works and how you can use it to work for you regardless of what your weight or fitness goals are. For example, your BMR decreases as you age, but it will increase the more muscle that you build. Both of these factors can foster weight loss or gain, depending on what you desire.
The basics of BMR
The body needs calories in order to produce energy and each person needs a certain number of calories in order to rest and do certain things throughout the day. For example, one person may live an active life, working out often and working a job that requires a lot of physical movement. They will require more calories per day for sufficient energy over someone who does not live an active life and sits or lies down much of the time. Essentially, each person will have a minimum amount of calories per day to not only stay alive, but also help when it comes to having the energy to complete their tasks.
Here is how you can determine your BMR:
Mifflin – St Jeer Formula – Currently thought to be the most accurate formula based on research by ADA.
Women: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) – 161.
Men: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) + 5
Harris-Benedict Formula – This is the old standard.
Basal Metabolic Rate for Women
Women: 655.1 + (4.35 x weight in pounds) + (4.7 x height in inches) – (4.7 x age in years)
Basal Metabolic Rate for Men
Men: 66 + (6.23 x weight in pounds) + (12.7 x height in inches) – (6.8 x age in years)
Once you calculate your BMR, then it is important to include your activity level because the more active you are each day, the more calories your body will need to produce the energy necessary to maintaing optimal function. Once you’ve determined your BMR, then determine your total daily energy expenditure (TDEE). In order to do so, calculate using the following method:
- Sedentary: BMR x 1.2
- Lightly active: BMR x 1.375
- Moderately active: BMR x 1.55
- Very active: BMR x 1.725
- Extremely active: BMR x 1.9 
If weight loss is your goal, understand that the step 1 is to consume less calories than your body needs each day and step 2 is eating a balanced diet (carbs, fats, protein, sugar, etc). So, let’s focus on step 1.
A good rule of thumb is to decrease your calories by 500 each day by eating less and by exercising. Then, over time you will lose weight because when you burn a total of 3,500 calories more than the body needs, you will lose one pound. By decreasing your caloric intake by 500 each day, within a week you will be able to lose between one to two pounds. Also, doing some weight resistance training a few times a week will certainly help you increase your BMR.
What’s great about technology is that there are plenty of websites and mobile apps that will help you out when it comes to determining your BMR. Go ahead and download an app that will keep track of your calories each day as you input the necessary information. The more you take control of your caloric intake and BMR, the more likely you are to reach your fitness goals more consistently.
- FreeDieting Calculator
- My Fitness Pal BMR Calculator
- IIFYM.com BMR Calculator
- Calculators and more info from Daily Burn
Factors that affect BMR
There are certain factors that affect your BMR and keeping these in mind will help you when it comes to weight loss or weight maintenance. Factors include your weight, age, gender, genetics, exercise and percentage of body fat you have. It’s essentially the number of calories your body needs if you were to have to stay in bed all day and evening.
Your BMR decreases over time
Health experts assert that your BMR decreases about 5 percent every 10 years after you reach 20 years of age. This is why people tend to gain weight as they get older and aren’t necessarily eating more. They’re simply experiencing a slower BMR, which can affect weight. Good news is that you can do things to reset your BMR as you age.
Typically, men have a higher BMR than women, as men usually have more muscle than women, although this doesn’t count for women who do serious strength training. For those that have a higher percentage or muscle, their overall body fat is lower, which gives them to have a higher BMR in order to keep that muscle. Additionally, your BMR increases as your body weight increases in both sexes. This means that the more you weight, the higher your BMR will be.
Why does my BMR matter?
It is important to understand more about your BMR whether you want to maintain your weight, lose weight, or gain weight. Knowing your BMR will help you maintain and achieve your weight goals over the years. In fact, sometimes those people who are having trouble losing weight and seem to be doing all the right things may just need to understand BMR a little better and apply it to their lives. Do the math and include this information as you continue to shape your healthy lifestyle.