It is a shame that most people are in such a quagmire about this topic. They see buff muscular bodies in magazines and men especially want to emulate. I was one of them almost 40 years ago. Luckily I discovered after only a few years of serious training that the protein myth is true. Calories are king. Carbs in particular. Get enough calories and you get enough protein. That is the only truth you have to know. So why do so many struggle with the muscle building dilemma? Simple. Time patience and experience. Let me humbly add my 35 years experience with vegan, raw, and fruitarian training (I am an all-around fit person not just "into" weights. In fact my cardio is off the charts. But as we all know that is easy to attain on a fruit diet. The training needed for endurance increase off the charts is easy compared to that needed for actually adding muscle size to your frame. And mine is a tall and skinny one, with genetic narrowing of the lower spinal channel as well as other joint problems as a result of a terrible automobile accident. Still was able to add quite a lot of muscle to my "hard gaining" frame with years and years of patience and focus. It is not rocket science! Please do not get caught up in these discussions to the point of researching this issue to death. As Emerson reminded us, books are good but "bibliomania" will suck your life away.
For the thousandth time lol.... milk ("liquid meat") and animal proteins have the highest nitrogen retention in the cells. So of course those who consume large quantities will puff up. This is not pure muscle just muscle "size". In addition however, the "growth hormone effect" from milk, whey protein powders, etc. and beef/chicken/fish to an extent will contribute as well. Plant proteins do not cause this inflammation of the cells due to a different prostaglandin structure. The bottom line is that building muscle REQUIRES lifting progressively heavier and heavier weights by using the large muscles of the human body (not wasting time on biceps curls, triceps kick-backs or pec deck machines or leg extensions or leg curls, for example) such as the "core areas" such as the hip/thigh/ back muscle structures. Getting enough calories and a little more and more and more as you get stronger, will eventually cause an increase in muscle size and this is also the only way to increase functional bone density, which is why every medical professional for the last 60 years has urged every person to do "weight bearing" exercise. It turns out that few ever understand how to do this right. It is quite simple! But since true weight training (not bodybuilding competition training or hobby) requires much more dedication and focus than say running or other cardiovascular activities (not to de-value them; just to compare the dedication and patience and focus that is mandatory to get even little results), few people do it. Of course those who look "big" and "muscular" are usually on steroids, or at least they consume animal foods and take protein powders designed to inflame and puff up the body. As Harley has pointed out many times, this is the marketing of muscle size. You can achieve a truly impressive body however with none of the above, just simple carbs like fruit and enough greens to round out your nutrition requirements. The main thing is to get enough calories! But without the day in day out month in month out year in year out (with periodization of course) progressive poundage increases in your squats and/or dead lifts, chins and dips, then this discussion will never ever be put to rest. THIS is not rocket science. It just takes work, focus and dedication. If you want to also be healthy, never get sick, never feel fatigued, and always be happy however, you had better do it with fruit! Sure you will be smaller (everything else equal) than the steroid or milk glutton, but heck! At least nobody will smell you coming a mile away. :)