The usual dietary prescription for someone looking to gain muscle is to simply eat more calories. But the more I've looked into and thought about this, the less this simplistic notion makes sense. I think the problem is in looking at calorie intake as an input, when really it seems to be more of an output or result of training.
If someone is looking to build muscle, they first have to stimulate this process through resistance training. If a growth stimulus is correctly applied, then the body should naturally want more calories to facilitate growth, and signal this need through more hunger. I feel the body is smart enough to know how many calories it needs, and that listening to hunger signals will be more efficient than trying to increase calories by a set amount.
Trying to force-feed calories just seems like a bad idea to me, as it is an attempt to override the body's natural system of hunger and satiety. There is also the issue of whether the growth stimulus is really effective or not. If a person isn't lifting weights with enough intensity and volume, then any force-fed calories will just go to fat.
Another issue is timing. After resistance training, when does the body actually need nutrients to make muscle? The bogus six meals a day idea says food should be eaten every three hours "just in case" that's when the body decides to create muscle. A more logical approach would be to listen to the body. If you're hungry, you're hungry for a reason: you body is seeking food for some metabolic process. (This assumes you are eating natural/Paleo foods and the hunger is genuine.)
For example, a few weeks ago I had a bad weightlifting workout - nothing seemed to work and the workout didn't feel productive. The next day, I wasn't really hungry at all, and that was probably because I didn't get the growth stimulus right. Conversely, yesterday I had a solid workout at the gym, and today I was very hungry. So I listened to this hunger and ate a good bit today.
In this way, you could view hunger the day after a workout as a test of whether the workout stimulated any growth. If you're hungry, it did; if not, maybe the workout was off the mark.
Regardless, I still find no reason to supersede the body's regulatory systems and try to force calories in order to build muscle. Instead, I will simply try to get in good workouts, listen to my body, and just eat when I'm hungry.
