Firstly know this: You don’t more than 2g/kg of BW of protein, as recommended by some ‘experts’ out there.
Yes, even if you want to gain muscle or lose fat or whatever, you only require about 1.2 to 1.5g/kg of BW.
However, there is no issue ingesting up to about 2g/kg of BW.
Know this about high protein intake: If you are not working hard in the gym or otherwise, excess protein will convert into fat.
And yes, your kidneys have to work harder to process the excess intake of protein. Nothing wrong in that, kidney by nature is build to work hard:)
Now, coming back to the question:
You can get enough protein if you are vegetarian.
Did you know that a cup of broccoli (300g) has about 10g protein?
Eating enough variety of veggies with your meals is good enough to give you about 15–20g protein daily.
You can read thispost I wrote for people who are vegetarians and how they can consume more than 100g every day.
Our body needs amino acids (building block of proteins) in varying quantities. Essential amino acids are as the term suggests that they are ‘essential’. Our body cannot manufacture them, and therefore need it from the outside source.
Many vegetable sources of protein are lacking in some essential acids, and therefore a need to eat the variety of food items to ensure you getting a steady supply of essential amino acids to make protein synthesis possible!
Hope this helps!