Some are fast and some are slow – people throw around the “m” word all the time, but do you actually know what metabolism is and how it works? It’s a lot more complex than you might think, but once you understand the basics you might finally get those results you’ve been chasing for years! Let’s dive into metabolism and everything you need to know about it.

Our bodies are constantly working and burning energy, our heart is beating, our lungs are breathing and we’re burning up (or metabolizing) those calories all day long. In the most basic way, metabolism is the process our body undergoes when it takes the energy from the food we eat and uses that to power our body. Everything that contains energy like molecules from food, sugars, fats, amino acids and so much more is extracted through metabolism. The rate at which that metabolism happens (our metabolic rate) is different for all of us and there are a few different things to take into account that make up our metabolic rate…

Basal Metabolic Rate (BMR)

Our BMR is the amount of energy we burn when we are resting – It reflects the minimum amount of calories your body needs to keep your body alive and functioning. This rate is different for everyone. There are many equations and online calculators available that you can use to get an estimate of your BMR, one popular method is the Harrison-Benedict revised formula: (just remember this is an estimate!)

BMR = 447.593 + ( 9.247 x weight in kg ) + ( 3.098 x height in cm ) – (4.330 x age in years )
BMR = 88.362 + ( 13.397 x weight in kg ) + ( 4.799 x height in cm ) – ( 5.677 x age in years )

Be Honest With Your Activity Level

This is where most people assume they’re more active than they really are. Be honest about where you fall into the categories below. Then Multiply your BMR by the number chosen below to give you a better guide of your TDEE (metabolism) – remember, this changes day to day, nothing is set in stone and we never really know for sure how many calories we are burning each day.

1.2 – Sedentary: You work a desk job and don’t exercise

1.375 – Light Activity: You work a desk job but do a bit of regular exercise. Or you don’t exercise but you work at a job that’s pretty active (a nurse, teacher, etc.) where you’re on your feet most of the day.

1.55 – Moderate Activity: Most of you will probably fall into this category. Maybe you work a sedentary job, but you train like a madman. Or maybe you train moderately, but you also have a job where you stand on your feet all the time. Someone who doesn’t train but works a hard labor job would also fall into this category.

1.725 – Very Active: You train hard most days of the week, and you also work a job where you’re on your feet quite a bit. Overall, you’re active most of the day.

1.9 – Extra Active: You train hard and work a job that is physically intense in nature. As an example, you’re a roofer who also goes to the gym five days a week.


Why would I want to know my BMR?

For people who want to lose weight, they would need to consume a little less than their TDEE to create a calorie deficit, and those who want to gain weight or muscle would need to consume a little more to create a calorie surplus- and those who want to maintain need to keep at that same level and their weight and body composition won’t change. It all comes back to calories in vs calories out.

Fast vs Slow

Now, we all know one friend who seems to be able to eat whatever they want, never gains any weight, and puts it’s all down to their “fast metabolism” (damn those lucky people!) Then, on the other hand, we have the slow metabolizers who feel like they really have to work hard and watch what they eat or their metabolism just doesn’t keep up. SOOOO why is this? Someone who has a big TDEE (metabolic rate) will have a faster metabolism than someone who has a lower TDEE – it’s simple science – they are burning up a whole lot more energy and because they burn so much, they are able to eat more without gaining weight. Remember, calories in vs calories out – the more that we burn (expend) the more we can eat/drink without any effect.

So, these are the very basic beginnings of metabolism (TDEE). We could honestly go on for days as there are so many factors contributing to our metabolism and it changes over time depending on your age, weight, activity level, and history of dieting. If you want to learn more, get to know your own metabolic rate and use it to your advantage (science doesn’t lie!) then send us an enquiry and get on the way to reaching your health and fitness goals the sustainable way and learn how to keep that weight off for good. #nofaddietshere

Norton, L Baker, P 2018, Fat Loss Forever, Chapter 2&3.