What Are Macronutrients & What Do They Mean For Your Workout?

What Are Macronutrients & What Do They Mean For Your Workout?

Matt Paterson (B.Ex & Sports Sci)

The building blocks of your nutrition that help your body to function, macronutrients are critical to human life. Even if you don’t pay attention to them, they are silently doing the work of keeping your body running as you consume them from your diet.

While you can just let macronutrients do their work without paying them any mind, you can also be more mindful about which ones you consume and in what quantity. The practice of tracking and manipulating macronutrient quantities in the diet is called “counting macros,” and it’s particularly popular among athletes, bodybuilders, and people trying to lose weight.

In this article, we’ll explain what macronutrients are as well as how they affect your training.

What are Macronutrients?

The term macronutrients refers to the three types of nutrients that humans must consume in large quantities in order to fuel their body and its processes. The three macronutrients are carbohydrates, proteins, and fats. This in contrast to micronutrients, which are just as important as macronutrients but can be consumed in smaller amounts. Micronutrients include things like vitamins and minerals.

Manipulating which macronutrients you consume and in what amount can affect how your body produces and stores energy, which can have a significant impact on health and fitness outcomes such as athletic performance and body fat percentage. That’s why many diet plans focus on macronutrient consumption, namely increasing or decreasing consumption of certain macronutrients and/or manipulating the timing of macronutrient consumption.


Carbohydrates are the body’s primary fuel source. They come from starchy, sugary, and/or fibrous foods and provide your body with glucose, which it converts to energy to support bodily functions and physical activity. Many different types of cells prefer to use glucose as their source of energy. In particular, red blood cells and the brain are only able to produce cellular energy from glucose. Glucose is also the main source of energy for physical activity at the start of and during short bursts of exercise.

Carbohydrates can come both in healthier and less healthy forms. For example, vegetables, fruits, beans, and whole cereal grains such as wheat, maize, and rice are all abundant in carbohydrates as well as other important micronutrients. On the other hand, highly processed or refined foods and foods high in sugar can be damaging to the health as they contribute to weight gain and promote diseases such as diabetes and heart disease. Further, they’re a less favourable source of energy as the body metabolizes them much faster, leading to spikes in blood sugar energy followed by sudden dips.

The Australian government’s Acceptable Macronutrient Distribution Ranges (AMDR) recommends getting 45–65% of your daily calories from carbohydrates.


Protein can serve as a fuel source but its primary role in the body is as a building block of body tissue. Proteins are comprised of amino acids, nine of which are essential for the body to receive from food. Without these nine amino acids, you will become malnutritioned and ultimately die. The nine essential amino acids are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine.

The main dietary source of protein is meat, dairy products, fish, eggs, grains, legumes, and nuts. While meat is very high in protein, certain forms of it, such as those high in saturated fat, red meat, and processed meats are linked with health risks and diseases such as heart disease and cancer.

The AMDR recommends getting 15–25% of your daily calories from protein.


While it is often maligned, dietary fat is in fact essential to give your body energy, support cell growth, protect your organs, maintain body temperature, produce hormones, and absorb nutrients. Like with the other macronutrients, different sources of fats are more or less healthy. Sources of the healthier unsaturated fats include vegetable oil, nuts, seeds, and fish. In contrast, trans fats and saturated fats have a proven negative effect on your health, increasing the risk of diseases such as heart disease. Common sources of unhealthy dietary fats include butter, red meat, and other processed foods such as packaged chips and cookies.

The AMDR recommends getting 20–35% of your daily calories from fat while limiting the intake of foods containing saturated fat.

How Macronutrients Affect Your Training

Being that they are so closely tied up with your energy and ability to build muscle tissue, macronutrients can have a big impact on your training.

For example, not getting enough carbohydrates in your diet can lead to having low energy levels, which can affect athletic performance. Your body stores glucose in the muscles as glycogen and uses this as an energy source during physical activity. If you don’t have enough stored glycogen to meet the demands your workout places on your body, you may feel tired and lack the energy to perform to the best of your ability. This is particularly a concern for endurance athletes such as runners and cyclists, whose bodies need available energy throughout the course of a long, high-intensity workout. This is why many endurance athletes “carb load,” in order to increase glycogen stores in their muscles.

Similarly, not getting enough protein can pose an issue for strength athletes or those who resistance train. When you train your muscles, you are actually damaging them by creating micro-tears. Your body requires amino acids to repair the muscles and build new muscle tissue. This is how muscle grows. If you don’t provide your body with the necessary protein to repair and rebuild your muscles, you will experience a loss of muscle mass and strength.

Finally, fat can not only serve as an additional source of fuel and energy during your workout, but it also helps your body maintain healthy levels of hormones such as testosterone which helps you build new muscle by stimulating protein synthesis, keeps your bones strong, preventing injury, and helps to control body fat percentage.

At the end of the day, eating a healthy, balanced diet with a sufficient amount of each macronutrient will help you perform at your best, giving you enough energy to push through your workouts and allow you to properly recover from them.

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