I'm torn on this subject. You can't build muscle without protein. Carbs can't be converted to amino acids but protein can be converted to glucose so it seems to make sense to err on the side of more protein. Plus, all the health issues regarding diet has to do with excessive carbs and fat which would comprise the majority of you calories if you are only getting 200 calories from protein a day.
Still, how the hell do gorillas get so big and strong being mostly vegetarians? Other than eating termites and ants it's mostly fruits and vegatables.Where do they get the protein to support such incredible muscle mass?
I backed off on protein because i am prone to uric acid kidney stones - a genetic trait on my father's side. It shows up pretty quickly on high protein diets and if i go keto - it can happen in a week.
I used to buy into the high protein diet as a way to build muscle but i think the science still isn't settled on that. I am lean at 185, at a height of 5'9". Right now I sit at 200, pretty much rock steady. I cut my protein to less than 100 gms per day almost exactly one year ago. Haven't changed weight at all- and still lifting the same poundages as being on high protein.
When I was racing bicycles I hung around with a lot of sprinters - guys with monstrous quads - who got them from lifting and sprint intervals. None of them ever was on a high protein diet. In fact they all ate carbs like they were going out of style. I used to travel with a few of them and saw it all first hand.
The biggest legs on a cyclist I have ever seen btw were on Eric Heiden. I was racing in Milwaukee and he was there for the pro events. I stood next to him briefly and was blown away. 28-30" I'd guess. And Heiden was very well known for eating junk food all day long. These guys absolutely did not do high protein diets. Pictures don't do him justice. In his cycling days he was actually smaller than he was while speedskating and yet he was a monster.