I used to do high protein diets and have over a long time supplemented my diet with protein powders just like most people here. I never felt really good with the high protein intake, disclaimer: I think 30 % protein is high!
While doing research for a health issue and the best treatment I read a lot about diet and have come to the conclusion that we Americans are obsessed with protein. Protein is a essential nutrient but we don't need large amounts of protein.
The recommendation is to eat about .8 to 1 gram of protein for each kilogram of bodyweight (1 kilogram is 2.2 lbs). The average adult needs about 60 to 70 g.
I think the confusion comes from the fact that proteins are made up from amino acids. We have a need for amino acids not protein. Humans cannot make 9 of the 22 amino acids that are needed and therefore must be consumed with diet. We need all of these 9 essential amino acids for our body to make protein.
The claim is that fish, meat, milk and eggs are high quality protein and can be easier absorbed by our body but I found little credible evidence that this is actually true and instead I found lots of references that the intake of large amounts of animal protein, particulary milk and meat cause health problems over the long term. There is overwhelming evidence that casein from milk (and dairy products) promotes cancer (it doesn't cause cancer but promotes cancer growth). Despite of that high amounts of protein are still recommended but if you really look closely it is mostly sponsored by the meat and dairy associations.
Soybeans, quinoa and spinach are high quality protein. Other protein sources of non-animal origin usually have all of the essential amino acids, but the amounts of one or two of these amino acids may be low. For example, grains are lower in lysine (an essential amino acid) and legumes are lower in methionine than those protein sources designated as high quality protein. They still deliver essential amino acids which are necessary for the body to build protein. We don't have to eat all essential amino acids we every meal as long as you have a variety of of different foods that contain those amino acids over the day or even over several days.
These days I don't count calories and macronutrients but checking through my journals my protein intake is about 10 to 20 %. With the exception of fish once or twice a week I have gone vegan. I have never felt better, I have blood tests done every couple of months and my protein levels were not effected at all by the change in diet, what was effected were my cholesterol levels which dropped to 150 total cholesterol with my good cholesterol being higher than the bad cholesterol and my other blood work is off the charts.
In the meantime, I am working out 5 to 6 times per week, including long distance running, I am visibly building muscle and losing bodyfat.
If you are concerned about your protein intake you may want to consider spirulina powder. Spirulina is a easily digestible, contains all 9 essential amino acids and is in fact second only to egg with regards to usable protein.
Sorry this was so long-winded. HTH.
