Protein is a source of energy but its main role in the body is growth and repair. Protein is a building block- it helps in the formation of muscles, hair, nails, skin and organs, such as the heart, kidneys and liver. We all contain a significant amount of protein. For example, a 76kg man is made up of 12kg of protein (16%).
Protein is found in both animal and plant foods.
Protein is made up of 20 amino acids. While all 20 of these are important for your health, 9 are classified as essential and 11 as non-essential.
All animal foods, as well as soybeans (a plant-based source of protein), provide all 9 essential amino acids in sufficient quantities and are classified as complete proteins. All other plant-based sources of protein lack one or more of the essential amino acids and are called incomplete proteins. People who follow a plant-based diet should eat a variety of plant sources of protein every day (e.g. legumes, nuts, seeds, whole grains) to get all the essential amino acids.
These values are taken from Protein | Nutrient Reference Values for Australia and New Zealand. The following examples show how daily protein requirements can be met:
Most of us easily meet (and surpass) the RDI for protein. Even vegans and vegetarians who eat a relatively balanced diet can easily get enough protein in their diet. In saying that, a lot of us don’t distribute protein well throughout the day- we tend to eat little at breakfast, a bit more at lunch and then a significant amount at dinner time. Ideally, we should focus on having a good serving of protein at each meal. This helps keep hunger at bay (as protein makes you feel full) and helps muscle growth/retention (Paddon-Jones et al., 2008).
Protein helps to make you feel full after eating, so including protein-rich food at each meal can help those people who are trying to lose or maintain their weight.
However, excessively high protein diets are not recommended, especially those omitting other food groups, such as grains or vegetables and fruit. Weight gain is a result of the energy taken in being more than the energy burnt off through metabolism or activity, irrespective of the source of the energy (kilojoules/calories).
Last reviewed: 02/02/2022
Last modified: June 22, 2022