Comment by adrian_b

Eating enough protein is also important, especially for older people, to prevent the loss of muscular mass, but that does not change the fact that the food must also include enough "fiber".

The US had for a long time a much too low recommendation of around 0.8 g of protein per kilogram of body weight per day.

That has been discredited by various studies. It is an amount that is sufficient to keep you alive, but it is not sufficient to keep you in good health until an old age.

It is not known with any certainty which is the optimum amount of protein intake. On certain lab animals protein restriction lengthens life, but for now there is no evidence that this also works for humans. Too much protein is known with certainty to be harmful for humans.

I believe that it is likely that the optimum protein intake is somewhere between 1.2 and 1.5 grams of protein per day and per kilogram of body weight, for a person with no overweight. For an overweight person, the protein needs do not increase proportionally to the total mass, i.e. the extra fat does not need much protein.

I wonder whether the so low protein recommendation of USA was actually intended for average Americans, which are likely to be overweight, in which case that number might provide an adequate protein intake.