Macronutrients are what make up the caloric content of our food. You’ve probably heard them referred to as “macros” and they are comprised of three categories:
The caloric combination of the macros is where we get the total number of calories.
Protein (4 calories per gram)
Proteins are the building blocks of life. The body needs protein to repair and maintain itself. Every cell in the human body contains protein. It is a chief component of the skin, muscles, organs and glands.
Protein is also found in all body fluids, except bile and urine. Protein is needed in the diet to help the body repair cells and make new ones. The nutrient is also important or growth and development during childhood, adolescence and pregnancy.
When proteins are digested, amino acids are left. The human body needs a number of amino acids to break down food. Amino acids need to be eaten in large enough amounts for optimal health.
Amino acids are found in animal sources (e.g. meat, fish and eggs), plant sources (e.g. soy beans, legumes, nut butters) and some grains (e.g. wheat germ).
The amount of protein required for effective function will vary significantly from person to person. In the UK it is often the case that the only decent amount of protein eaten during the day is the evening meal. Protein should be a major part of every meal consumed. A basic starting point to work out how much protein you need is to consider body weight and physical activity levels.
Carbohydrates (4 calories per gram)
Carbohydrates are an ideal source of energy for the body. This is because they can be converted more easily (than proteins or fats) into glucose, which is the form of sugar that’s transported and used by the body.
Although it’s an ideal energy source, a diet too high in carbohydrates can upset the delicate balance of the body’s blood sugar level, resulting in fluctuations in energy and mood. This can result in feelings of irritability and tiredness. It’s better to balance the intake of carbohydrates with protein, a little fat and some fibre.
Carbohydrates are often thought of as the primary source of energy in the human body. This is not completely true, however because it depends on what the body is doing at the time.
During normal daily activities, both carbohydrates and fats contribute significantly to energy requirements, but as the intensity of activity increases, the contribution from fats diminishes and the contribution from carbohydrates increases.
Fats (9 calories per gram)
Fat is a major source of energy, it helps the body absorb vitamins and it helps foods to taste good. Fats are an especially important source of calories and nutrients for infants and toddlers, and they play a major role in determining cholesterol levels.
The level of cholesterol in the blood has become a key risk factor in the pathology of cardiovascular disease.
The grand total?
The total amount of calories should be divided across each of the macronutrients to achieve the following ratios:
- Minimum of 50% of total calories from carbohydrates.
- Maximum of 35% of total calories from fats.
- Minimum of 55g of protein per day (9-12% of total calories).