As a 180 pound male I find the RDA for the essential amino acids total 17.5 grams. However, the RDA for protein is 64.8 grams. Where does this nearly 4x difference come from?

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    Protein = multiple types/groups of amino acids. Essential amino acids = a single group of amino acids. In other words, because different sources of protein contain different ratios of each of the amino acids. The social use of the word "protein", is very vague.
    – user19679
    Jun 18, 2016 at 7:58

2 Answers 2


In the human body, there are 21 amino acids (AA) that can form proteins (Britannica). Only 9 of them are essential, meaning you have to obtain them from food; the other 12 can be synthesized in your body (MedlinePlus).

Most food proteins contain most essential and nonessential AA, so to get 17.5 g of essential AA from proteins, you need to consume more than 17.5 g of them. Anyway, 65 g of protein (RDA) will probably provide more than 17.5 g of essential AA, because RDA does not include only the essential amount of protein but a bigger amount with a wide safe margin.


Proteins are made of twenty different amino acids. Among these, only about ten are essential amino acids, which means the body cannot synthesize them from other amino acids. This explains the difference.

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