What is a macronutrient?

Nutrition Blog

Macronutrients are nutrients which provide calories or energy. Nutrients are substances which are needed for growth, metabolism and for other body functions. Since ‘macro’ means large, macronutrients are those which are required in large amounts.

There are three macronutrients:

While each one of these macronutrients delivers calories, the number of calories that each one provides is vastly different:

  • Carbohydrates provide 4 calories per gram.
  • Protein offers 4 calories per gram.
  • Fat delivers 9 calories per gram.

This means that if you had a look at the Nutrition Facts label of a particular product – and it said 12 grams of carbohydrate, 0 grams of fat as well as 0 grams of fat per serving – you would know that this food has about 48 calories per serving (12 grams of carbohydrate multiplied by 4 calories for each gram of carbohydrate = 48 calories).

Besides carbohydrate, protein and fat, the only other substances that provides calories is alcohol. Alcohol provides 7 calories per gram however it is not a macronutrient because we do not need it for survival.

What are the athletes’ macronutrient needs?

For athletes engaged in serious physical activity, nutrition is crucial. It can improve endurance, speed up recovery from exertion, lower the risk of injury and assist in rehabilitation:

  • Carbohydrates are the gold standard for athletic performance. They supply the brain and body with power and also produced stored glycogen. Complex carbs are the preferred fuel for muscles and the brain, and they should constitute the largest percentage of calories in the diet. Foods in this category include whole-grain breads, high-fibre cereals, pastas, rice, beans, fruits and vegetables.


Starch and glycogen are the body’s two most important carbohydrate energy contributors. Starch is available in plant foods while glycogen is available in animal foods. When starch is consumed, it digests slowly so releasing glucose steadily into the bloodstream. The glucose is stored in the liver and muscles in the form of glycogen until it is needed by the body. Generally speaking, athletes need between 6 and 10 g of carbohydrates per kg of body weight per day.

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High protein intake may compromise the carbohydrate intake which, in turn, can negatively affect the ability to train or compete at peak levels. Protein intake above the recommended levels can result in diuresis (increased urine formation and release) and dehydration.


  • Protein supplies the body with building blocks, which are called amino acids, that are essential for the growth and repair of lean tissue. Of the 22 amino acids, eight are essential (cannot be made by the body) and must be obtained from food. Athletes should be sure to eat well-rounded, complete protein sources which can be found in lean meats, skinless chicken, shellfish, soy, eggs and low-fat milk products. Athletes require 1.2 – 2g/kg of body weight in protein per day (compared to 0.8g/kg for sedentary individuals).


  • Fat is vital for the production of key hormones and neurotransmitters in addition to cushioning the organs. Diets which are high in bad fats (trans and saturated) are linked to many diseases but certain fats – namely linoleic acid (n-6) and alpha-linolenic acid (n-3) – are essential for normal growth and health. It’s important to emphasise healthy fats (n-6, n-3, polyunsaturated, monounsaturated) while trimming total fat intake.

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