This word “metabolism” is thrown around a lot these days. You’ve probably heard that if yours is too slow you might gain weight.  But what exactly does this mean? What exactly is metabolism?

Well technically “metabolism” is the word used to describe all of the biochemical reactions occurring continuously in your body.  It’s how you take in nutrients and oxygen and use them to fuel everything you do. And it’s these biochemical reactions that keep your body alive and functioning.

There are three ways your body utilises energy from the food you eat:

  • Voluntary activities (activities you can control) i.e. physical activity
  • Involuntary activities (activities you can’t control) i.e. heart beat, wound healing, and processing of nutrients & toxins
  • Storage of excess energy

All of these processes together make up our metabolism. So, you can imagine that these processes can work too quickly, too slowly, or just right.

Which brings us to “metabolic rate”. 


This is how fast your metabolism works and is measured in kilojoules (or calories). Metabolic rate is influenced by many factors including gender, age, amount of physical activity, muscle-to-fat ratio, and hormone function.

So, it makes sense that the more kilojoules you burn the easier it is to lose weight and keep it off because there will be fewer “leftover” kilojoules to store. On the flip side, if we eat and drink more kilojoules (energy) than we need for our metabolism and exercise, we will store it mostly as fat.

Your body’s metabolic rate (or total energy expenditure) can be divided into three components:

  • Basal metabolic rate (BMR) = how much energy (kilojoules) your body uses at rest i.e. when you’re not being physically active. This is the energy your body uses to keep all of its systems functioning properly and accounts for approximately 50-80% of your daily energy use.
  • Energy used during physical activity = this component contributes approximately 20% of your daily energy use.
  • Thermic effect of food = the energy used to eat, digest and metabolise food, which contributes approximately 5-10% of your energy use.

What affects your metabolic rate?

In a nutshell: a lot!

1. Thyroid

This gland at the front of your throat releases hormones to tell your body to “speed up” your metabolism.  Of course, the more thyroid hormone there is the faster things will work and the more calories you’ll burn.

2. Your size 

Larger people have higher metabolic rates; but it’s your body composition that is crucial! 

Muscles that actively move and do work need more energy than fat does.  So the more lean muscle mass you have the more energy your body will burn and the higher your metabolic rate will be.  Even when you’re not working out. This is exactly why resistance training is often recommended as a part of a weight loss program.

The thing is, when people lose weight their metabolic rate often slows down, so exercising to build and maintain lean muscle mass is crucial.

3. Aerobic exercise

This temporarily increases your metabolic rate.  Your muscles are burning fuel to move so they’re doing “work”.

4. The type of food you eat

Your body actually burns kilojoules to absorb, digest, and metabolise your food.  This is called the “thermic effect of food” (TEF). You can use it to your advantage when you understand how your body metabolises foods differently. 

For example, fats increase your TEF by 0-5%; carbohydrates increase it by 5-10%, and protein increases it by a whopping 20-30%.  By including adequate lean protein you can slightly increase your metabolic rate. Another bonus of protein is that it has been shown to help you feel more full and prevent you from overeating, as well as being crucial for muscle growth and development (to help build that lean muscle mass).

5. The mind-body connection 

There is plenty of research that shows the influence that things like stress and sleep have on the metabolic rate.

But, all this is just the tip of the iceberg when it comes to metabolism. There are so many different things that can work to increase (or decrease) your metabolic rate.

If you want to talk about your metabolism and how we can get it working for you, then don’t hesitate to contact us.

Recipe: Protein-rich Lemon Herb Roasted Chicken Breasts

Serves 4-8

  • 2 lemons, sliced
  • 1 tablespoon rosemary
  • 1 tablespoon thyme
  • 2 cloves garlic, thinly sliced
  • 4 chicken breasts fillets (skinless)
  • dash salt & pepper
  • 1 tablespoon extra virgin olive oil

Preheat fan forced oven to 180°C.  Layer ½ of the lemon slices on four pieces of foil.  Sprinkle with ½ of the herbs and ½ of the sliced garlic.

Place one chicken breast on each piece of foil and sprinkle with salt & pepper.  Place remaining lemon, herbs and garlic on top of each chicken breast.  Drizzle with olive oil.  Wrap each chicken breast into a parcel with the foil.

Bake for 20-30 minutes, or until chicken is cooked through. 

Serve & enjoy!

Tip: You can add a leftover sliced chicken breast to your salad for lunch the next day!

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