We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
I'm talking about lifters who are working on strength and muscle-building for 3+ hours/week. For muscle repair and renovation, such people need from 70-90 gms of protein daily depending on their size and body type.
Serious strength-builders also need more carbs and fats/oils than non-lifters. It's near-impossible for men to gain significant strength without gaining some weight (muscle weight, not fat weight). Women are different because they can not normally build muscle bulk.
Sedentary or cardio-exercisers need around 40 gms of protein daily. That does not include people in marathon training. And don't forget that there is some protein in everything we eat, so vegetarians can build strength as well as carnivores as long as they consume enough volume.
HOWEVER, nobody's body can use or metabolize more than 20-25 gms of protein in 3 hours. Anything more than that goes to waste or into body fat (yes, excess dietary protein can go to body fat). That's why lifters eat multiple small meals daily rather than the conventional three - to keep a stream of usable protein flowing.
A nice steak contains 70+ gms of protein, so most of that steak goes to nutritional waste. However delicious, it's recreational eating - something Americans specialize in. I love a t-bone occasionally but am under no illusion that I need it. It's for enjoyment.
(Other examples: a chicken breast has around 70 gms protein, an egg about 8 gms, a McDonald's burger about 20 gms, a cup of green beans about 2 gms, a cup of yoghurt or milk 8 gms, a cup of oatmeal 6 gms. )
It needs to be said that most of the diet of weight lifters is not about what their body "needs" but rather about making their body have good muscle definition. That to some extent they aren't simply weightlifters but in fact are body builders. Not that there is anything wrong with choosing to eat in a way that reduces your bodies subcutaneous fat, I went through that phase myself. But the point is that eating in a way that makes you look "cut" or shows off your muscles is simply not the same thing as eating to build strength. In fact the two diets are contradictory and you cannot be both a body builder and a weight lifter. Look at the weight lifters and all the top lifters are huge and don't look like Arnold Schwarzenegger did.
There is of course a third category of people who lift weights and do other exercises to improve fitness and health. This does not require a special diet. You could simply eat any diet complete in essential nutrients with no problems.
I've read so many different opinions on protein consumption. Currently, I'm going with erring on the side of more, rather than less, especially as I slide into late middle-age. This is the article that convinced me, and it seems to work: https://www.mensjournal.com/food-drink/youre-not-eating-nearly-enough-protein/
As with all nutrition advice you can find "evidence" for any and all opinions. It doesn't help that a) proper experimentation is hard and b) everyone (including researchers) has a pet theory. Having lived through butter good - butter bad eat margarine - margarine bad butter ok and eat carbs / carbs bad manias I've decided that nobody truly knows anything.
I've read a lot of books / articles about nutrition and come to the conclusion that I haven't a clue about what a "good" diet is, nor does anyone else.
So I'm left with reading a lot and experimenting. I'll go take a look at the Mens' Journal article linked by Joe Y . . .
Now, I know that there are numerous studies showing various opinions on protein intake and how much your body can use. As an aging lifter and being concerned with quality of life as I can older I have been doing some reading on the topic. The older body doesn't use protein as efficiently therefore we need to consume more protein. Some studies do find that you cannot overdue protein consumption. Fat gain from excess protein consumption could have more to do with caloric intake rather than the amount of protein.