What is Basal Metabolic Rate?

If you want to lose weight, you need to create a calorie deficit. It’s only when you provide your body with fewer calories than it requires that you’ll start to burn fat. No deficit? No weight loss!

But how do you know how many calories you should eat? After all, if you don’t know your starting point, how can you create the necessary deficit?

While you could guess and just eat 500-1000 fewer calories less than usual, you’ll probably get better results if you know your basal metabolic rate or BMR for short. Your BMR is a measure associated with your daily calorie expenditure and requirements.

Knowing it will take a lot of the guesswork out of weight loss and weight management. In this article, we reveal what Basal Metabolic Rate is, how to calculate it, and how to use this number to help you lose weight more quickly and easily.

Basal Metabolic Rate – A Complete Guide

Definition of Basal Metabolic Rate or BMR

Your body is burning calories constantly, even when you are asleep. The processes of breathing, moving, and even thinking use energy.

Your body works non-stop! Your BMR is the number of calories your body needs to fuel these processes at rest. BMR is the amount of energy your body needs to maintain its most basic functions.

In fact, if the term basal is a little confusing, swap it for the word basic to make BMR easier to understand. Your BMR is the amount of energy your body uses at rest and without factoring in the energy used for physical activity or even the digestion of food.

If you sit or lie still for 24 hours, your BMR is the amount of energy needed to sustain you during that time. Knowing your BMR can be useful for weight loss purposes.

BMR Formula and How to Calculate It

The easiest way to determine your BMR is to use one of the many free online calculators and weight loss apps. Just tap in your height, weight, and age, and you’ll get your result in seconds. Alternatively, you can use a formula, such as the Harris-Benedict equation.

This formula is one the most popular, although it’s not necessarily the most accurate. That said, while other formulas exist, they’re often so complicated that you need a math degree to use them!

Harris-Benedict provides an acceptable level of accuracy without needing a NASA computer for the calculation. There are two formulae – one for men and one for women.

While they can look confusing, these formulae are actually relatively easy to use. Just remember to do the parts of the equation in brackets first, and the rest is relatively simple.

Remember too that there are 2.2 pounds in a kilo, so make sure you convert your weight into kilograms before starting. Similarly, there are 30.48 cm in a foot and 2.54 cm in an inch. So, if you are a 40-year-old man who is 5’ 6” and 180 lbs., your Harris-Benedict calculation would go like this:

Weight in KG = 81.81       Height in CM = 167.64

66 + (13.7 x 81.65kg = 1118.6) + (1.8 x 167.64 = 301.8) – (4.7 x 40 = 188) = 1298.4 calories

How To Use Your BMR To Lose Weight

Now you know your BMR, you can use it to determine how many calories you need to consume to lose weight. However, before you can do that, you also need to factor in how much physical activity you do per day. After all, physical activity burns calories too.

To do this, simply multiply your BMR by the appropriate activity factor listed below. This will provide you with your Total Daily Energy Expenditure, or TDEE for short. This is the number of calories your body needs for its essential metabolic functions and physical activity.

So, using our previous 40-year-old man’s BMR and assuming he is moderately active, this would produce a TDEE of 2012.52. That’s:

1298.4 x 1.55 = 2012.52 calories

To lose weight, you need to consume fewer calories than your TDEE. A 500-calorie deficit per day should lead to a one pound per week weight loss. You CAN cut your calorie intake more aggressively than this and lose weight faster, but it’s seldom a good idea to consume less than your BMR.

Doing so can lead to severe hunger and could leave you feeling low on energy and unable to function correctly. You may also lose muscle mass, which would actually lower your BMR. Easy ways to lower your calorie intake include:

  Eating less fat

  Eating smaller meals

  Cutting out snacks

  Missing a meal or two per day (intermittent fasting)

  Drinking calorie-free water instead of soda, juice, or milk

  Replacing high carb foods with lower carb alternatives, such as less bread and more veggies

Alternatively, you can exercise more to increase your calorie expenditure. In fact, most people find it easier to lose weight if they combine exercise with a healthy diet.

Bottom Line

A lot of diets specify how many calories you should eat per day, such as 1200, 1500, or 2000. However, these figures do not take into account your BMR or your TDEE. For some, these values could be too low and lead to extreme hunger and fatigue.

For others, they could be too high and lead to weight gain instead of weight loss. Adjusting your calorie intake according to your BMR and TDEE means that you can personalize your calorie intake, eliminating much of the guesswork from dieting for weight loss.

Once you know your TDEE, you can use an app to track your food intake and make sure you have a calorie deficit but also that your deficit is not so large that your diet is unsustainable.

However, it’s important to understand that even the most accurate BMR formula or advanced TDEE app is still nothing more than an estimate of your caloric needs. Even if you hit your numbers every day, you may still find that you lose weight slowly or even fail to lose weight at all.

Don’t despair; this just means your BMR calculation missed the mark, and you should just adjust your food intake until you start seeing the progress you want. Think of BMR as a good starting point but be prepared to make adjustments according to your progress.

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