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The importance of protein

Along with carbohydrates and fats, protein make up one of three major groups of macronutrients which provide the body with the energy it needs.

They play an essential structural role since they are present in all the body’s tissues and provide the building blocks for the manufacture of enzymes, hormones, neurotransmitters and antibodies.
Proteins are basic components in the formation of “lean body mass”, in contrast to body fat.

Proteins are long-chain compounds consisting of a sequence of different amino acids, some of which may be manufactured by the body whereas others can only be obtained from consumed food. Since the human body is unable to synthesise these latter compounds they are known as essential amino acids, of which there are 8.
So that they can be absorbed via the gastrointestinal tract, the proteins’ long chains must be cleaved into smaller chains by digestive enzymes.

The various sources of proteins

Protein-rich foods include milk, eggs, fish and meat as well as cereals and legumes.

Animal protein sources are the most “complete” since they contain all the essential amino acids which the body requires. Egg white in particular is the “perfect” protein.

Plant protein sources may only contain a small amount of certain essential amino acids. Because of this, if the diet consists exclusively of plant proteins then the individual needs to combine different types of plants, such as legumes and cereals, in order to cover the body’s requirements for essential amino acids. 

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Nutritional requirements for proteins

For a healthy person, with no particular pathology, the diet should provide, as a minimum, 1 g of protein per kg of “ideal” or healthy weight. This level of protein intake ensures the correct renewal and functioning of tissues and organs under normal conditions. 

Calculate your “healthy weight” 

One way to calculate your healthy weight is work out your body mass index (BMI) which defines a healthy weight range.
        BMI =  weight in kg/(height in m)²

An individual’s weight is considered to be healthy if his or her BMI is in the range from 18.5 to 25 kg/m². If the BMI is below this range then the individual is said to be underweight, whereas anyone with a BMI of between 25 and 30 is said to be overweight; or obese if their BMI is over 30.

Using this measure, a healthy weight corresponds to a BMI of 22 to 23. For example, for a person 1.65 m tall, a BMI of 22 corresponds to a weight of 60 kg. 

However, in certain situations, this intake of protein is insufficient and must be increased. This is particularly the case for overweight people looking to lose weight. In this context, demands are placed on the body and more protein should be consumed.

Indeed, to lose fat rather than lean body mass, you must “feed” this lean body mass by consuming approximately 1.2 g of protein per kg of healthy weight.

This intake ensures that the body’s physiological requirements are met. It makes it possible to lose weight comfortably (without feeling hungry) and while staying healthy (maintaining lean body mass and losing fat). 

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Sources :

  • Eve Villemur (2018) Maigrir grâce à mes 3 cerveaux. Published by Leduc.s
  • Website of the French Agency for Food, Environmental and Occupational Health & Safety products:  https://www.anses.fr/en/content/proteins