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Why do we need macronutrients?

In the fitness industry and on social media you hear a lot about ‘macros’ and how much we should eat of them. But what do people mean when they talk about these macros? What are the functions of these nutrients? And how much should we eat of them?

First it’s important to know that there are 6 classes of nutrients in our nutrition. These six classes of nutrients are:

  • Carbohydrates

  • Fats

  • Protein

  • Vitamins

  • Minerals

  • Water

The carbohydrates, fats and proteins are called the macronutrients. The body needs these nutrients in large amounts. They’re the nutrients that give you energy. Macronutrients contain the components of food that the body needs to maintain its systems and structures.The vitamins and minerals are called micronutrients. The body needs much smaller amounts of these nutrients.


Carbohydrates often get a bad name, especially when it comes to weight loss. But carbs aren’t bad at all. Carbs are actually essential for our bodies.

Functions of carbohydrates in the body:

  • Providing energy (4 kcal/gram).

  • Storing energy (glycogen in the liver and muscles).

  • Carbs contain fibers. Fibers are essential for optimal digestive health.

  • Oxidation of fat (some carbs are needed to burn fat).

The amount of carbohydrates needed per day ranges from 3-12 grams of carbs per kilogram of body weight. It depends on the amount of movement you get, and how intense this workout is.

Recommended intake range: 3-12 g/kg/day

Light intensity: 3-5 g/kg/day

Moderate intensity: 5-7 g/kg/day

High intensity: 6-10 g/kg/day

Very high intensity (elite athletes): 8-12 g/kg/day

So for a person who walks 1 hour every other day, the range of 3-5 grams/kg body weight per day is recommended. If this person weighs 65 kg, 195-325 grams are the recommended amount of carbohydrates per day.

For someone who cycles 5 times per week for 2 hours, the range of 6-10 grams would be recommended. This means 390-650 grams of carbohydrates for a person of 65 kilogram.

Another method to determine the amount of carbs needed without weighing yourself, is to take 40%-70% of your daily energy (kilocalories) from carbohydrates. You take 40% and 70% of the amount of kilocalories you need. So when you need 2200 kilocalories this is 880-1540 kcal. These numbers you divide by 4, because each gram of carbohydrates contains 4 kilocalories. So for the example this means 220-385 grams of carbs per day.


Fats are also regularly talked about in a negative way. But the body needs them as much as any other nutrient. Fats are a source of energy for the body. Besides that it also contains vitamin A,D, E and K. There are saturated and unsaturated fats, fats from nutrition is a combination. Products with a lot of saturated fats increase the risk of heart disease.

Products with many saturated fats:

  • Butter (roomboter)

  • Cheese

  • Meat

  • Coconut oil

  • Palm oil

  • Mayonaise

  • Fried food

  • Chocolate

This doesn’t mean that you should ban these products, it means you should not eat too much of them. You should replace the saturated fats with unsaturated fats.

Products with many unsaturated fats:

  • Nuts and seeds

  • Vegetable oils

  • Avocado

  • Fatty fish

Functions of fat in the body:

  • Providing energy (9 kcal/gram)

  • Storing energy (in fat cells)

  • Healthy and stabilises hormones

  • Important for eyes, brain and muscles

  • Fat satisfies hunger

  • Cells need fatty acids as building blocks and to protect the cells against unwanted invaders

20%-40% of your daily energy (kilocalorie) intake should come from fats. The main sources should contain mostly unsaturated fats.


In the fitness industry, protein has a big name. This is because physically active people have a higher need for protein. There are plant proteins and animal proteins. Plant proteins are in products like bread, cereals, legumes and nuts. Animal proteins are in products like meat, fish, dairy, cheese and eggs. There are also proteins in meat replacements.

Functions of protein in the body:

  • Providing energy (4 kcal/gram)

  • Growth and maintenance of tissues

  • Enzymes are proteins that aid the thousands of biochemical reactions that take place within and outside of your cells

  • Some proteins are hormones, which are chemical messengers that aid communication between your cells, tissues and organs

Adults need 0,8 grams of protein per kilogram of body weight per day. For some people this number is higher, like vegetarians, vegans, physically active people, children and pregnant people.

Average adults: 0.8 g/kg

Adult athlete: 1.2-2.0 g/kg

Recreational athletes or more endurance training focused: 1. 2-1.5 g/kg

Strength training: 1.5-2.0 g/kg

Vegetarians: 20% more than the recommendation

Vegans: 30% more than the recommendation

Post Exercise recovery: 15-25 g or 0.3 g/kg

*In this article I mention the amount of grams you should get from a certain nutrient. To know if you meet this recommendation, you would have to track your nutrition. Tracking your nutrition is not for everybody. In the last article I wrote about intuitive eating.


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