All food we consume contains energy, and falls into one of three categories – protein, carbohydrates and fat – also known as macronutrients. They are named macronutrients because they are nutrients that our body requires in large amounts, as opposed to micronutrients that I’ll talk about in a separate article. Each macronutrient has different roles in the body and some are more important than others.
It is important to understand the roles each macronutrient plays when trying to manipulate the diet to achieve certain physique goals. Adjusting the quantities of each macronutrient in diet will lead to different outcomes, whether that be influencing muscle mass, fat mass or strength.
Let’s start with protein, seeing as though the name comes from the Greek word proteos, meaning ‘primary’ or ‘first place.’ Protein has a multitude of roles in the body and our body is in a constant state of building it up and breaking it down. Protein can’t be stored by the body in the same way fats and carbohydrates can, which means it’s essential to eat it consistently for adequate nutrient intake.
Protein makes up hundreds of functional components of the human body, ranging from antibodies in the immune system that fight off viruses, to enzymes that carry out chemical reactions, to structures like hair and nails. Specifically, with regards to strength training and fat loss programs, adequate protein is important for the recovery of muscles. One gram of protein contains four calories of energy.
Just like protein, fats also have a variety of functions in the body. Fat can be broken down for energy, it’s the primary component in steroid hormones (like our sex hormones and corticosteroids), it forms our cell membranes, brain and nervous system, and it transports fat soluble vitamins, A, D, E and K.
Fat also comes in two types naturally: saturated and unsaturated. Unsaturated can be further split into two groups: monounsaturated and polyunsaturated. Saturated fats have been labelled in recent decades as ‘bad’ fat, but actually it is a necessary part of our diets, and it’s a good idea to have an even split of saturated, mono- and polyunsaturated fats in your food. There is, however, a third type of fat, trans, that you want to avoid. Trans fat is artificially produced to lengthen the shelf life of products and offers only detriments to our health, and has even been classified by the US Food and Drug Administration as not ‘generally recognised as safe’. Trans fat is commonly found in margarine, and some peanut butters and cooking oils, and it’s best to avoid using these products completely, if you can.
Fat is the most energy dense of the macronutrients, boasting 9 calories per gram, more than double protein and carbohydrates.
Carbohydrates are our bodies’ preferred source of energy. Once consumed, carbohydrates are broken down to glucose and the fate of that glucose is determined by your energy needs. In a high energy situation, such as exercise, glucose in the blood is used for energy. If energy is not immediately required, glucose can be stored in either the form of glycogen or triglycerides (fat). Glycogen can be found in primarily the liver and muscles, ready to use when the time comes for a lot of energy to be expended quickly, or when we haven’t eaten in a while and our blood sugar is low. When glycogen stores are full, glucose is converted to triglycerides.
Triglycerides, which can also be found in the liver and muscles, primarily resides in fat cells. So, when more carbohydrates are consumed than are necessary, they can increase fat mass. Carbohydrates also have 4 calories per gram, just like protein.