The Basics of Macros

Macronutrients, micronutrients, vitamins, minerals – nutrition is a complex topic, and one that is surrounded by unfounded claims, myths, and “bro science”. Macronutrients (or “Macros”) are probably what comes to mind for most athletes when they think about their own nutrition. The major macronutrients are: protein, carbohydrates, and fats. People used to think that fat made you fat; now people claim that carbs make you fat. And of course, you’ve been told you need to eat as much protein as possible to get “jacked”. Enough with the myths, let’s do a brief overview of macronutrients.


Carbs are your muscles main fuel source. Your body stores carbs directly in your muscles in the form of glycogen – long chains of glucose. When you exercise your body breaks the glycogen down into individual glucose molecules, which it then use to make ATP, which provide the energy for your muscles to work. Your liver stores carbs as glycogen too, but the process of your body using liver glycogen as fuel during a workout is much slower and so doesn’t happen to a major extent until later on in your workout.

After you exercise your muscle glycogen stores are depleted, meaning you need to eat carbs in order to build the stores back up so that you’re ready for your next workout. Before exercise carbs have been shown to be beneficial as well. It gives your muscles extra, readily available glucose molecules that it can use more quickly and easily than the stored glycogen.


Yes, as you probably know, you need protein to build muscles. However your body doesn’t use protein in the form of whole proteins, it first breaks down the proteins you eat into their individual amino acids before absorbing and utilizing them. There are 20 different natural amino acids and of these there are 8 are considered essential amino acids, meaning that your body can’t make them and you have to get them through your diet. In terms of muscle building the most important amino acid is leucine; it actually activates the anabolic pathway, via mTOR, to help build muscle.

Protein has other uses in the body than just supporting muscles and strength. All the enzymes in your body, which are responsible for all sorts of chemical reactions, are made from proteins. Immunoglobulins, which are a huge part of your body’s immune defences, are proteins. Amino acids are also used as, or converted into, different neurotransmitters within your body such as glycine and gamma-aminobutyric acid (GABA). And, if you don’t have enough stored glucose or fat, you will actually breakdown your body’s proteins into their individual amino acids and then convert certain amino acids into glucose for energy, through a process called gluconeogenesis.


Fats are your main fuel source for endurance exercise. Your body processes fats much more slowly than carbs but when exercise lasts a long time your body knows that glycogen alone won’t last and finds a balance between burning carbs and fat to provide your muscles with the energy that they need to sustain your workout.

Fat is also important in athletes because fats, specifically cholesterols, are used to make your hormones. Hormones are very important to everyone and athletes are no exception. Insulin, Glucagon, Cortisol, Glucorticoids, Testosterone, Thyroid hormones, Human Growth Hormone, Insulin-like Growth Factor, and Ghrelin are just some of the important hormones that are important to, and affected by, your workout – and you can’t make them without fats and (good) cholesterol.

As a general rule of thumb, healthy fats should make up a MINIMUM of 20% of your daily calories to help keep your hormones in check.


Hopefully now you have an understanding of some of the roles the different macronutrients play in your body. Each of the different macronutrients are important; how much of each you should aim to have every day depends on your body composition, weight, height, and most importantly your goals. Very generally speaking, most athletes should be getting somewhere in the range of 20-25% of their calories from protein, 40-55% from carbs, and 20-40% from fats. These numbers are rough because every person is different, with different needs, different digestive systems, and different goals.

Written by: Nick Plagos