How Your Basal Metabolic Rate Affects Weight Loss

March 12, 2015
basal metabolic rate, bmr, weight loss, total energy expenditure, calculate

How well do you really know your body? You know that you need a cup of coffee to wake you up before your morning meetings, and you know that if you don’t go to bed before 10pm you’ll be yawning all day tomorrow.

But what about what’s inside your body and how it actually works? Do you know how your individual body works when you do things like exercise or eat fatty foods? You may not know your body as well as you think you do if you haven’t calculated your basal metabolic rate.

RELATED: Top 5 Dieting Myths Dispelled

So you’re thinking, oh, I have a quick metabolism, so I can eat that donut, or that your period is coming soon, so as your metabolism speeds up, you can eat that whole block of chocolate. Seriously, who hasn’t thought something like that before? If you haven’t, then you might need to relax with your food sometimes.

Your metabolism varies from person to person and also from day to day. When you get stressed, your metabolism speeds up, which is why people lose weight when they’re stressed. It also speeds up the week before your period and varies due to your exercise and diet.

Your basal metabolic rate or BMR can be calculated through an equation, and though it won’t be 100 per cent accurate, it can give you a good idea of what your body would burn if you were to lay in bed all day, which is essentially what the BMR is. It calculates the amount of calories your would burn if you stayed in bed for 24 hours and makes up 65 per cent of your daily usage.

There is then another equation that can be used to approximate the amount of kilojoules burned during the day from the type of lifestyle you lead, which can then help you in your quest for weight loss. How does this work?

Once you have worked out what your BMR and total daily energy expenditure are, you can start to count your food calories to measure what you put in, versus what is burned out. By knowing how much your body burns daily, you can then plan your food to make sure you are capable of losing weight with the diet that you are on.

Do you want to know the magic formula? According to Women’s Health & Fitness, your BMR can be calculated by using this equation:

BMR = 655 + (9.6 x weight in kg) + (1.8 x height in cm) – (4.7 x age in years)

For example, my BMR would equate to 655 + (9.6 x 53) + (1.8 x 160) – (4.7 x 20), which equals 1357.8. This figure is in calories, so you then multiply by 4.18 to equal the kilojoule amount, which mine would be 5675.604.

This is, in theory, what your body would burn all day if you laid in bed. If you’re freaking out and cutting down meals in your head, don’t worry, there’s another part to add depending on your activity level. Multiply your calories or kilojoules by your activity rate to find what your body would burn daily when you exercise.

Sedentary = BMR x 1.2 (little or no exercise, desk job)
Lightly active = BMR x 1.375 (light exercise/ sports 1–3 days per week)
Moderately active = BMR x 1.55 (moderate exercise/ sports 6–7 days per week)
Very active = BMR x 1.725 (hard exercise every day, or exercising 2 times per day)
Extra active = BMR x 1.9 (hard exercise two or more times per day, or training for marathon, triathlon, etc.)

To give you an example, mine would be 5675.604 x 1.55, because I am moderately active. This equals 8797.19 kilojoules that my body would be burn during the day.

While this is still a theory, you can work out a food plan that is suited to your body and your BMR. Then, if you need a little extra expenditure, you can add in a couple of intense workouts to give you the lenience of going to that Italian restaurant on a Friday night. Bellisimo!

Who would’ve thought that a maths equation would help you in the gym?

Images via Best Nutrition

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