Overview of the macronutrients: proteins, carbs and fats

So in this post i will give you a simple overview of the macronutrients, also referred to as “macros”. These are the nutrients we need in larger quantities compared to the micronutrients which we need in smaller quantities. The macronutrients are proteins, carbohydrates and fats.


The primary function of proteins is to protect, repair and build new and existing tissue in the body. When you digest protein the body breaks them down into their amino acids. There are 2 types of amino acids: essential and non-essential. Essential amino acids come from your diet whereas non-essential amino acids can actually be created by the liver. Eating 1 gram of protein burns 9 calories. This is more than double compared to carbohydrates and fats below. Which is why high protein diets are often associated with better weight loss. You can get protein from a number of animal sources e.g. poultry, fish, beef, egg, etc and from non-animal sources e.g. lentils, chickpeas, most types of beans, green-peas and chickpeas. Its worth pointing out that vegans and vegetarians will need to eat a variety of protein sources to get all the essential amino acids from the protein whereas diets with animal sources will have the essential amino acids already.


For carbohydrates the primary function is to provide a fuel source for our daily activities. Carbohydrates come in the form of sugars and starches so foods like bread, rice, potatoes will be high in carbohydrates. When you digest carbohydrates your liver will turn some of them into glucose which is stored in your liver and muscles to be used later as an energy source. Eating 1 gram of carbohydrates burns 4 calories.


The primary function of fats is to store energy. Eating 1 gram of fats burns 4 calories. It’s important to understand that there are 3 types of fats.

  1. Trans fats: Which are mostly made from saturated fats which have added hydrogenated oil. These can often be found in fried and baked foods as well as doughs. Trans fats should be avoided and if they are already in your diet you should make an effort to reduce the amount you consume.
  2. Saturated fats: Not as bad as trans fats but you should aim to reduce your consumption of saturated fats to about 5% of your daily calories. Saturated fats have been linked to higher cholesterol and an increased risk of cardiovascular disease. Saturated fats are commonly found in animal sources such as poultry, red meats and full fat dairy products.
  3. Unsaturated fats: Commonly known as the healthy fat. This is because they can decrease the risk of heart disease. They can be found from plant sources such as avocados, nuts, seeds, olives and some oils. Ideally you want to increase your healthy fat intake while decreasing unhealthy fat intake.

Why you need to check them

Checking and adjusting your protein, carb and fat intake can have major benefits to your diet. For example if you have a high fast energy carbohydrate breakfast in the morning you could feel hungry again by around 10-11am. This could lead you to snack to fill that hunger pang which could make you eat excess calories and derail your progress. By increasing the protein in that meal and decreasing the carbohydrates you can feel less hungry until your next meal and hopefully not overeat by snacking. Its important to understand here that theres nothing wrong with having a snack just that it should fit into your plan instead of eating a snack because you’re so hungry from the previous meal. It’s also very important to recognise that no macronutrient should be avoided. There are far too many “no/low carb” diets out there that claim carbs are the enemy. Carbs are not the enemy in your weight loss journey. Often when people cut out carbs in their diet it makes them miserable as they remove a vital source of energy from their diet. When I personally tried no/low carb it made me very irritable and often I would derail on that diet because I just couldn’t stick to it.

How they impact your BMR

As shown earlier you burn 9 cal/gram for protein, 4 cal/gram for carbs and fats. This means each gram you consume your body has to burn those calories just to digest the food. The higher number for protein is why high protein diets are often shown as diets with better weight loss results. A higher protein diet not only requires more energy to consume but also it makes you feel full for longer therefore the need to snack (and overeat) is minimised.

There we have it, a quick overview of the macronutrients. Theres a lot more we could have covered but as a quick overview and how these macronutrients affect BMR and why you need to check them is a good starting point for most people out there. As always if you have any questions let me know below or feel free to contact me.

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