Except for the last several thousand years only the very wealthy or those living in protein rich environments had any appreciable protein intake at all. You were happy to eat meat once a week if you lived in Europe in the 1800s.
True. But neither did they have an overabundance of sugar and fat. I am not pushing eating more meat. The Protein Leverage Hypothesis is quite fascinating though. As one nutritionist and science writer put it “the amount of protein you eat could determine the total energy consumption since the appetite for protein is so strong that we keep eating until we get to our target protein intake. If we eat an unbalanced diet that contains a low percentage of protein we increase the total energy ingestion in order to get to our target protein intake.” Vegetarians and vegans could pay more attention to ensuring that they get adequate protein through the right combinations in their diet.