I heard that it takes about 2500 calories to build 1lb of muscle.
I was wondering if those 2500 calories had to come from protein only.
For instance, if one is trying to stimulate 2lbs of growth per week instead of 1, will he need twice as much protein, or will the P/F/C ratio remain the same?
Well if muscle was all protein, it would be about 1818calories per pound. However, muscle is is pretty low percentage protein; majoratively muscle is creatine, glucose stores, water. That’s not to say you should keep your protein low; however you can’t really force your body to gain 1kg of muscle per week just by eating heaps of stuff. However, if you keep your protein constantly high and a stimulus there, muscle will grow, just not controllably. But so will a lot of fat generally 
I would keep the ratio the same, but that’s just me.
This is the way I look at it. You have to find a compromise between gaining lots of muscle and fat. You’ll pretty much never gain just muscle, unless you’re special. The more you up your calories, the more chance there is that those calories will become fat. This is simplified of course, not counting cardio and other things.
Plus, if just protein built muscle, wouldn’t we all just eat protein all the time, so we’d be huge and ripped? Obviously, it doesn’t work like that.
Base your macro ratios on past experience, or on how your body reacts to most food. I’m a skinny bastard, and I require lots of carbs to grow. You may be different. Experiment with different ratios, and keep a close eye on weight, bodyfat%, etc.
Good Luck
To simplify things even a little bit more-- too much of anything will turn to fat. If you ate 9000 calories a day of pure protein, you would get fat, not to mention the havoc it would wreak with your gastrointestinal system.
RIT Jared
Ok. I see what you guys mean.
But I still don’t understand how it works.
There is about 600 calories in one lb of muscle. I guess this includes the glycogen in it.
That would mean that the process of building one lb of muscle takes about 2500-600 = 1900 calories.
Now here’s the point…
You will note that it is often said that to gain muscle, you must take about 1g/lb of protein, which is about 200g or so.
This means that MOST of the caloric excess of a traditional bodybuilding diet in fact comes from protein. More precisely, it means 130g more than for someone sedentary, which means about 520 cal per day, or about 3500 calories per week. That is 1-2lbs per week, which is what is supposedly possible to gain.
So… it seems that those 2500 calories should really come from protein for the biggest part. Otherwise, we would take much less than 1g/lb of protein.
See what I mean… I’m not sure I made myself clear… lol
Another thing I would add before I finish is that when I tend to eat increase significantly more carbs when I bulk, I seem to gain quite a lot of fat. So maybe all those carbs are not needed and end up stored as fat.
Shotgun,
Of course, while it does take protein to be able to construct new muscle, there is no direct controllable link between the type of food consumed and how our body uses it. Hmm, and don’t assume your body can reassemble muscles from proteins without spending energy.
In particular, the experts on here have talked about how it takes a lot of energy to construct new muscle. This energy will most likely be able to come from fat and carbohydrate sources as general fuel for your metabolism.
Also, keep in mind that there is protein turnover in the body. Muscles don’t only grow, they are broken down as well. So, one reason to eat a lot of protein is to help moderate the breakdown by keeping amino acid levels elevated. This is also one of the reasons it is suggested to eat many small meals.
Find some articles on here about protein and also on post workout nutrition. They will talk a lot of general issues concerning anabolic and catabolic activity as well as how to help push the body into an anabolic state.