Macros – what they are an how many you need

You will often hear the term macros bandied about when it comes to nutrition, particularly when it comes to losing fat or putting on muscle, but what actually are macros and why should you care about them?

The foods we eat basically contain two types of nutrients – Macronutrients (or macros) which we need a lot of and micronutrients, which we only need very small quantities of. Micronutrients include vitamins (such as vitamin C, D, B12, etc.) and minerals (such as iron, zinc, pottassium, calcium, etc.).

Macro nutrients fall into the following categories; carbohydrates (including fibre), fats, protein & water. Fibre, although mostly indigestible, is essential for health, particularly in maintaining a healthy gut. The role of fibre is covered in this blog post.


Carbohydrates are the main source of energy for your body. While most cells in the body can use both fat & carbohydrates for energy, carbohydrates are the preferred form. Carbohydrates are classified as simple (sugars) and complex (starch and fibre).

Sugar occurs naturally in fruit, milk and honey as well as in plants such as sugar cane and sugar beet. However, a large proportion of the sugar we consume is processed – it has been extracted and concentrated. Complex carbohydrates are found in root vegetables (such as potatoes), grains (oats, wheat, barley, rice), beans, peas, lentils and vegetables.

Carbohydrates should make up at least 50% of your diet. However, not all carbs are equal. You wouldn’t want 50% of your diet to be sugar, because while it provides energy, it is absorbed into the bloodstream very quickly and disrupts your blood sugar balance. You can find out more about this in the blog post about the glycaemic index.

Instead, your carbs should come from starchy foods, such as bread, rice, potatoes, beans, lentils and vegetables. Again, not all of these carbs are equal – highly processed white flour, although still starch, converts to sugar so rapidly, it has a high Glycaemic Index and leads to rapid increases in blood sugar.

Wholemeal bread and whole wheat pasta are much better options, as they have more fibre (see this post on why that’s important) and raise blood sugar much more slowly. Rice is a bit of an anomaly as both white and brown rice have high glycaemic index, however, Basmati rice has a different type of starch, which gives it a low GI. Eat your potatoes with the skin to lower the GI.


Fats have been demonised in the past, in the false belief that a high-fat diet made you fat. Fat doesn’t make you fat. Excess calories make you fat! Fat has several important functions to play in the body. It is a source of energy, it protects your internal organs, it insulates you from the cold, it is needed for cell growth, development & repair and provides essential fatty acids, such as Omega 3, 6 & 9. For women, fat is important for the production of Oestrogen, so having too little fat can lead to reproductive issues as well as increasing the risk of osteoporosis.

Fat also adds flavour to food, it gives food a more pleasant texture in the mouth and because it takes a long time to digest, helps to keep you feeling fuller for longer. Fat has just over twice the calories of carbohydrates, gram for gram, though, so the calories can quickly add up. However, you should still aim for 30% of your daily calories to be fat.

Fat falls into two main types, saturated and unsaturated. Saturated fats are solid at room temperature, they include most animal fats (lard, butter, bacon fat, goose fat, etc), as well as coconut and palm oil. A diet high in saturated fat is associated with an increase in bad cholesterol (LDL), furred arteries and heart disease.

Unsaturated fats are liquid at room temperature, they mainly come from plants, such as sunflower oil, olive oil & nut oils, but also include fish oil. Unsaturated fats are split into two further groups, poly and monounsaturated fats. Polyunsaturated fats often provide essential fatty acids which we can’t make in our own body, such as Omega 3 & 6. These can be found in fish oils, flaxseed oil & rapeseed oil.

Trans fats (hydrogenated) are thought to be even worse for you than saturated fat. They are found in margarine (however check the label), baked goods and many processed foods. You should minimise your intake of trans fats.

As you can see, the right types of fat aren’t bad for you and a very-low fat diet can be damaging to your health. Beware of low-fat products in the supermarkets, as they have often had the fat replaced with sugar, which is far from beneficial.


Protein is essential for the growth, maintenance and repair of body tissue, in particular muscle. All enzymes and some hormones in the body are proteins, as are anti-bodies, a vital part of your immune system. Protein should make up between 10-20% of your diet.

Proteins are made up of amino-acids, some of which can be made by the body, some of which cannot and therefore need to be obtained through our food. Animal products contain all the amino-acids we can’t produce ourselves, however, plants do no single plant does. This means that vegetarians and in particular, vegans, need a wide variety of dietary protein, to ensure they get all the required amino-acids. Fortunately very common food combinations, such as peanut butter on wholemeal bread, rice & beans, or beans on toast, provide the required amino-acids!

Most people have more protein in the diet they need. The exceptions are usually body-builders and those who follow a vegan diet. How much protein do you actually need? Well, that’s covered in-depth in this blog post, but around 0.8g per kg of body weight is enough for most people. If you’re on a calorie deficit, to lose weight, then increasing your protein intake can not only help you feel fuller, it will also minimise muscle loss, although that needs to be partnered with some strength training, too.

Protein is found in meat, fish, eggs, dairy products, nuts, seeds, beans, peas, pulses and lentils. Some people choose to supplement their protein intake with shakes, however, your body can only process a limited amount of protein at a time. Excess protein will be broken down in the liver and excreted in the urine which can cause kidney damage, as well as being converted to fat and stored in the body, leading to weight gain. Eating a lot of meat, which may be high in saturated fat, can also increase the risk of heart disease.

In summary, your daily calorie intake should be 50-60% carbohydrates, 30% fat (but not more than 10% saturated fat) and 10-20% protein.

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  1. Pingback: Food Labelling – understanding the nutritional information – Revive Fitness Classes

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