This one is a bit of a revisit because there are still so many going for this myth and I feel in needs more detail to make the point really clear.
Massive protein = Massive muscles
Because of course muscle is made of protein isn’t it? No actually it isn’t. Most of your muscle is water, so think of it less like a bunch of steel rods more as a bunch of incredibly tough water balloons, the sort that fortunately don’t tend to burst on impact.
The irony of the fact muscle is mostly water is that any excess protein that cannot be converted to fat is disposed of along with some excess water in your urine.
Yes you need protein, but the western diet contains proportionately more of it than we need. We eat very meat rich diets compared to our body design, the clue is in the massive canine teeth we don’t have.
When it comes to dealing with training and growth we need energy to train, protein to repair damage a comparatively little for growth, and here’s the big one, energy to fuel the repair process. The balance doesn’t shift much, you need more protein than someone sitting on their posterior all of the time but your energy demands are also higher so the percentage increase in protein need is not much different to increase in need for carbs, fats and trace foods.
The key here as anywhere regarding nutrition is balance. Don’t eliminate protein but don’t expect it to have the instant ability to convert you to Adonis either. If you are looking to gain mass I generally advise you have a little more protein than you absolutely need, the fat some of this will be converted to should burn away with your training if not excessive, and better to be sure there was enough. However if 50% of your calorific intake is protein, that will be why the love handles aren’t disappearing.
This is a bit vague and people will undoubtedly have looked at it and declared that it cannot be true because there is a picture of their favourite athlete drinking a protein shake and this rather than the years of training and genuine nutritional guidance is what is making them the way they are. They need a revenue stream and there are always supplement manufacturers ready to pay someone to tell the world how brilliant their egg, milk or other fluid designed to feed infant animals.
This is a more detailed look at what really happens with protein in the human body and why. It will explain why those of us who have read in any detail about nutrition don't use protein supplements but put the money toward better food instead.
Protein you can absorb and need
There is a reason we have quite pathetic canines, it's because we aren't designed to eat a lot of food that requires tearing, especially meat. This isn't an ad for vegetarianism, it is just to point out you don't have to look far to figure out that our bodies aren't set up for high protein intakes.
An area you can't see is your gut, the home of the limitation on protein intake. Due to the joy of genetic switches you can absorb 22 grams of protein in one go during or just after training. The rest of the time this is only 17 grams. I have seen protein drinks with over 30 grams in a serving, not including the milk. Obviously if you take this in over a period of time the gut will allow more past but swilling down a pint of supplement in one go that has over the amount you can absorb is the first of two ways the body will make you flush your money down the toilet. This form of excess will bind you up nicely, so it may be good to balance it out with some fibre, supplementing to allow for over supplementation. There is some genetic diversity on the amount you can absorb but it will be no more than a gram or 2 either way.
In your blood
To get into your blood protein has to be broken down into amino acids, not a surprise to many. These are basically the nutritional equivalent to time bombs in the body, which less are aware of. Every moment these amino acids are in your blood they creep ever closer to the point where they will break down to generate ammonia. For those who don't know, this is not a good thing, the reason you cringe at the smell of ammonia is because it is highly toxic.
There is some good news though. The body is so good at dealing with this, the damage caused due to ammonia generated from broken down amino acids during your entire life wouldn't present any danger to you if it happened in one go.
As much protein as needed will be used. Amino acids are used to repair and create new tissue, everything from muscle to blood cells have some protein in their construction. Enzymes are amino chains as are hormones etc. In fact it would be easier to list things that happen in your body that don't at some level rely on protein than do. When you see the lists it becomes a little more clear that the piffling amount of weight you want to gain in muscle each day amounts to virtually nothing, and most of the skeletal muscle use for protein will be repair not new growth.
Not so exciting excess
As stated in the original part post there is a greater need for protein when you train more, but this is balanced out by the additional energy need. Hitting protein harder generates a potentially harmful excess, as stated already though this doesn't present a danger your body isn't ready for.
The attitude of many seems to be that more protein would make more muscle, as if having an excess would encourage the body to add more lean mass than it deems necessary because it's there. There is a reason I am making this look ridiculous, because it is. Any organism that would waste resources in such a way would go extinct fast, carrying more muscle than needed is wasteful in terms of resources to build maintain and feed. Excess protein will not ever become more muscle just to use it up, your body just isn't that stupid.
What any organism wants for survival is a comfortable energy fall back, so anything that can be stored to provide energy for lean times will be. Some of the amino acids can be combined or converted to others that will combine to generate lipoproteins which is an elaborate word for fat. Any excess calorific substance that can be stored as fat will be and protein is no exception.
The small amount that cannot be must be disposed of before it becomes a danger and it is by converting it to urea in the kidneys and disposing of it in your urine, more supplement money down the toilet. The volume of water this takes with it is why short term high protein diets make you lose weight. As anyone who has used these will know it doesn't take long for your body to find it again when it needs to prevent dehydration.
I would say you would have to go a long way to find a trainer who hasn't tried high protein diets at least once, including me. I have sworn by some of them in my time but in truth I have gained far more from eating good quality food in balance than I ever did trying to second guess with supplements.
If you want to spend out on the latest mass gainer or weight loss plan that is basically high protein with a different name, go for it. Even if all you gain is a psychological advantage, that's worth it, but if you realise the shift is the opposite to what you wanted, there is a good reason for it, the real gains from high protein diets are 99% myth and the rest is for people with bad diets to start with or gaining by belief alone.