> In which cases are the animals more efficient?
When they are grazing on non-arable land and the alternative is to produce no food at all here.
About proteins, from the article you linked (the Harvard one):
> For a relatively active adult, a daily protein intake to meet the RDA would supply as little as 10% of his or her total daily calories. In comparison, the average American consumes around 16% of his or her daily calories in the form of protein, from both plant and animal sources.
> Based on the totality of the research presented at the summit, Rodriguez estimates that taking in up to twice the RDA of protein "is a safe and good range to aim for." This equates roughly to 15% to 25% of total daily calories, although it could be above or below this range depending on your age, sex, and activity level.
I'm not sure how you come to the conclusion that Americans are eating too much proteins, considering the article is not saying it, or even saying the opposite.
When they are grazing on non-arable land and the alternative is to produce no food at all here.
About proteins, from the article you linked (the Harvard one):
> For a relatively active adult, a daily protein intake to meet the RDA would supply as little as 10% of his or her total daily calories. In comparison, the average American consumes around 16% of his or her daily calories in the form of protein, from both plant and animal sources.
> Based on the totality of the research presented at the summit, Rodriguez estimates that taking in up to twice the RDA of protein "is a safe and good range to aim for." This equates roughly to 15% to 25% of total daily calories, although it could be above or below this range depending on your age, sex, and activity level.
I'm not sure how you come to the conclusion that Americans are eating too much proteins, considering the article is not saying it, or even saying the opposite.