I do not understand the idea of prescribing protein intake based on body weight.
It makes no sense to me.
Prescribing protein intake in such a manner suggests that the protein needs of a 28 year old 6’4” man weighing 220 pounds with 10% body fat is the same as a protein needs of a 28 year old 5’6” tall women weighing 220 pounds with 50% body fat.
This then suggests that body fat has a protein requirement equal to that of lean body mass, which is incorrect.
The other possibility is that daily act of moving a 220 pound body is what creates the protein need, which suggests that a persons protein need is created in part by doing work.
This makes more sense to me, however it suggests that active people need more protein then sedentary people at the same body weight, but that very heavy sedentary people may have similar protein needs to active people whom are comparatively very light, and this would again make a protein recommendation based on body weight less than ideal.
To the best of my knowledge a person’s protein needs are best equated to their total lean body mass.
And, total lean body mass from a population perspective is best predicted with height.
Furthermore, the demand for protein intake created by your lean body mass is largely made by your metabolically active lean body mass, your GI tract, and internal organs, not necessarily your less metabolically active lean body mass, i.e. your muscle mass. And organs and GI tract size correlates well to height.
This means that even if a 6’4” male and a 5’10” male have compatible amounts of lean body mass because the 5’10” male is a bodybuilder who has increased his muscle mass, the 6’4” male would still have a higher protein requirement because he would have more metabolically demanding lean tissue (organs).
When I raise this concern in academic circles the response has been, “Brad, it’s the easiest most accessible measurement.”
Height is the easiest most accessible measurement that is not prone to daily or weekly variations the way body weight is.
It also helps control for the large metabolic differences between metabolically active lean body mass like your organs and less metabolically active lean body mass like your muscles.
The bottom line is until we move away from suggesting protein intake based on body weight, we’ll forever be arguing over the ideal protein intake for any given population.