Everyone’s body burns a minimum amount of calories throughout the day to maintain life-sustaining functions, like breathing and brain activity. You burn calories even when you’re asleep. But how many calories do you burn? What are the factors that affect that number?
To answer these questions, you’ll need to calculate your Basal Metabolic Rate (BMR).
The Basal Metabolic Rate
Your BMR is the estimated number of calories that a person of your height, weight, age, and gender burns over twenty-four hours. Knowing your BMR allows you to understand how many calories you’ll burn in a day even if you didn’t exercise. Note that your BMR estimate can differ from your actual burn rate if you have more muscle mass than the average person.
For example, a bodybuilder with 10 to 20 pounds more muscle mass than an average person has a higher actual burn rate than their BMR estimates. This is because muscle mass burns more calories than regular body mass.
We’re going to work with BMR throughout this book, so let’s calculate yours now.
How To Calculate Your BMR
You can find various formulas for BMR online, but I use the ones below (known as the Harris-Benedict equation):
Men: 66 + (6.23 x Weight in Pounds) + (12.7 x Height in Inches) – (6.8 x Age in Years)
Women: 655 + (4.35 x Weight in Pounds) + (4.7 x Height in Inches) – (4.7 x Age in Years)
To understand this in practice, let’s calculate my current BMR. I’m a male who is 155 pounds, 71 inches tall, and thirty years old.
Here’s the math using the formula above:
66 + (6.23 x 155) + (12.7 x 71) – (6.8 x 30) = 1,729.35 calories a day
So, my BMR number is roughly 1,729 calories a day. Knowing this, I can assume that if I ate exactly 1,729 calories a day and did no exercise, I wouldn’t gain or lose any weight.
Now it’s your turn. Calculate your BMR and burn that number into your mind for the next few weeks and months. Remembering your BMR will help you make progress, so write it down.
Once you calculate your BMR, losing weight becomes a lot clearer. You can use it to calculate how much weight you will lose in a single day. You can even use it to calculate a daily calorie maximum intake if you want to lose a specific number of pounds by a certain date.
Many people pay personal trainers for an initial session just to understand their BMR. Now that you know how to do this for yourself, you can skip that session.
Use What the BMR Calculation Tells You
While we will add calories to our BMR number later for exercise, it is easy to assume that you burn more calories than what the BMR equation tells you.
Don’t be tempted to add extra calories to your burn rate. If you want to lose weight, the first step is to accept the baseline numbers so that you can build off them. While starting off, use the BMR equation above and work with the number you get. We can be a little bit more flexible later once the weight starts coming off.
So, You Calculated Your BMR. Now What?
Knowing that I burn at least 1,729 calories a day, I can calculate how much food I have to eat to lose weight. I can also calculate almost exactly how long it will take to lose 5, 10, or 15 pounds based on my “intake number,” or the number of calories I’m consuming each day.
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