Protein is a basic “ingredient” of your body, cells and also an important part of your nutrition. It may come from products of animal origin or fruits and vegetables. A well-known protein source is meat : the best are turkey and chicken, tuna, salmon, but we can’t ignore the dairy products, such as milk, cheese, yoghurt. 
Fruits with protein content: dried apricots, dates, figs, prunes, avocado, blackberries, raisins, watermelons, bananas.
Vegetables: beans, broccoli, spinach, soy, lentils, peas; all kinds of nuts and seeds: almonds, walnuts, sunflower seeds, etc. As you see, anything that you eat, in smaller or bigger quantities contains proteins. So, you don’t have to worry about not eating enough, because it is practically impossible not to eat them, even if you embrace a vegetarian lifestyle. 

 I hear a lot in the gym, that I should consume 2-2.5 g of protein per kg of my bodyweight. Well, I began counting the calories and found out that is like a circle made by the devil, because if let’s say you have a 1500 kcal goal and want to lose some kilos, and you are 65 kg, that would mean, that you would have to eat   between 130 and 162 g of protein a day. Well, that is enormous, because you have to stay in that 1500 kcal range. As a result, you will probably eliminate fruits and vegetables and mostly nuts and seeds from your meals because fruits have a lot of carbohydrates but a relatively small amount of protein, the vegetables that mostly contain protein are also high in calories. Seeds and nuts  have proteins,  also have a great, even huge caloric value compared to the amount of protein content. For example, 100 g sunflower seeds contain 27 g protein, (some sources indicate only 21 g) but they have 584 kcals!    So, you will probably reach to meat, because meat has 25-30 g of protein per 100 g, and because you wouldn’t probably be able to eat meat all the time, and would like some fruits from time to time also, you inevitably will have to rely on the protein powders, because they have a very reduced caloric value but huge amount of protein. For example, a protein isolate may have 30 g of protein to only 100 g of kcals. Well, that is something you will never find in nature. And then, the big producers of any powder out there got you right there, where they wanted. 

 But wait and just think about nature. Do you really think that if we would need such a great amount of protein, God wouldn’t have created the fruits and vegetables also with bigger protein content? Why is then that only certain foods have it, and the majority of foods don’t? Or do we think that nature is absolutely non-sense? Even if you go to the gym. How many of us do we train so many times, with such an intensity and for enough time that such an amount to be justified? 

 The common mistake comes from the fact that protein is a building block of any live organism and then after the logic of a five-year-old, it is assumed, that the more you consume of it, the bigger your muscles will become because the amount of protein eaten will somehow go and “put” itself on your biceps, for instance. If it would work like that, then anything would be sooooo easy. A lot of Arnolds and Cutlers would walk around. But they do not work like that. As I wrote in my other article about protein, a reasonable recommendation of the American Dietetic Association and International Society of Sports Nutrition recommends 0.8 g/kg for average people and 1.2-2 g/kg of body weight depending on the activity for a sportsman. That would mean for a 65 kg individual around 50-60 g of protein if he or she is an average person and if is a sportsman we are talking about 70-130 g, depending if the practiced sport is endurance (then should be close to the lowest level), for strength training the intake should be closer to the higher amount. Why is like this? Simple. If you do not have such a great muscle activity, you also will have nothing you would have to repair with the protein. Remember! The proteins main characteristic is to build, and only as secondary it is used to fuel the body with energy. (For that we use more carbohydrates). If you feed yourself with excessive portions of protein it will be deposited as fat, such as anything else. But if fat doesn't occur  in very large quantities ti is not life-threatening, but over-consuming protein can be, for other reasons. Over-doing something means that you also over-solicit your organism by having to digest it.  Meat, for example, stays 6 hours in your stomach. Just try it:  eat meat for lunch and you’ll see that you won’t get hungry as soon as if you would from some kind of vegetable. So, you didn’t even digest one meat, you would put some more in your stomach? Everything you have, may that be your leg muscles, your brain, your hair or your nails, they need rest. You can not put pressure on your leg all the time, because they will get tired and will start to ache, maybe you will have problem with your knee joint also, you can not iron your hair all the time with a straightener, because if you do, it will lose its brightness, the ends will split and break easier. You can not wear nail polish all the time, otherwise, it will dry your nails and maybe they will split easier also, becoming yellow meanwhile... 
So, everything you do, you have to make breaks time-to-time, otherwise, the organ will get tired. A split nail won’t cause you much besides some anger, but a sickness in your stomach, liver or kidney, is a much more serious business. 

 Yes, protein builds in some sense, but whatever the quantity is, it will not all end up becoming muscle. When you want to blow up a mountain, you’ll need a certain amount of dynamite, if you want to blow up a little hill, you’ll need a much smaller quantity. The same it goes for muscles. If you don’t have them, any way you kill yourself in the gym and drink tubs of protein shakes, it won’t make you “go big” in no time. Hard, long work and genetics do.