Comment by thesz

https://www.youtube.com/watch?v=lzsEqV0Bjcs - that lecture refers a simple formulae to compute protein content from the amount of nitrogen. They count nitrogen in grams, then multiply by 6 to get amount of "available" protein. But, any antinutrients such as cyanides will count as proteins by this calculation.

Lentils contain trypsin inhibitors, which contain inordinate amount of nitrogen that is counted as protein.

While you do not eat these directly after cooking your lentils, you do not eat as much protein as you would think you do.