You do not have to eat every three hours to gain muscle. You do not have to be constantly eating until you barf. You DO need to maintain a caloric surplus though.

Check out Robb Wolf's Norcal Strength and Conditioning blog post about a paleo mass gain here: http://www.norcalsc.com/index.php/index.php?/post/paleomass_gain_peter_m/

Also read up on www.leangains.com Specifically his newest post which gives logical answers to nutrition myths like "eat every three hours" here: http://www.leangains.com/2010/10/top-ten-fasting-myths-debunked.html

Martin Berkhan focuses on eating the majority of your calories in the post workout timeframe. That seems to put the emphasis on rebuilding damaged tissue and building new muscle. It has worked well for me and for many others.

Your main goal again is to have a caloric surplus. Rather than eating whenever you're hungry I would suggest trying to log your food into www.fitday.com and figuring out what's going on. Maybe you're always hungry because you aren't eating enough and need denser caloric foods. See the norcal post for a boatload of recipes.

Hope that helps.

I get stints where I am hungry a lot and so I eat a lot more. And I have stints when I'm not that hungry and so I eat less. I listen to my body and it seems to work. Another thing I have noticed is there are two kinds of hunger pangs. One is a slight bit of pang coming around the time I usually eat, as if my stomach is reminding me it's the usual time. Often, if I ignore that, it passes and then I can go hours before I get hungry again. That kind of hunger pang is more like a pang that comes out of habit. The other kind of hunger pang is the kind that if I ignore it, it keeps coming back and back and nagging me to no end and all I can think about is food food food for hours. All I can think about is food all the time for long hours. It's very annoying and I take that is evidence that my body is very very interested in food that day. So I listen and I eat.

If you are exercising a lot, it's natural to be more hungry. My instinct is to say eat more if you are REALLY hungry and see how that goes. I personally do not worry about what time it is when I eat. If I am really hungry and it's midnight, then I eat. If it's dinner time, but I am not hungry, then I don't eat. If you follow your hunger and eat healthy and do not start getting flabby, then it's most likely the right track for you.

Also, nutrition density is going to be very important for muscle building. I think fitday.com is very useful to monitor nutrient intake and where you may be lacking, but not useful for monitoring caloric needs. According to fitday, I should be getting fatter, not skinnier. But yet I am getting skinnier so that shows you what fitday knows about my caloric needs (ie nothing). Fitday can't tell you how many calories you need because metabolism and exercise and caloric expenditure vary hugely across individuals. Your hunger and a look in the mirror will go much farther towards telling you what you need than any fitday math formula ever will.

Edited to add: Many paleo eaters advocate fewer meals per day, which is fine by me under most circumstances. However, if doing such results in a person not being able to stuff down sufficient calories and therefore becoming underweight and often hungry, then by all means, eat more meals and get the calories you need if that is what you need to do!

Muscle protein accretion is always significantly elevated in the hours after a workout, particularly within a 2-hour window. It goes down progressively for the next 24 to 36 hours or so, reaching a point where it is very low.

Since you are slightly insulin resistance immediately after a workout, arguably the most important feeding period is between 30 minutes and 2 hours after the workout.

Eating nonstop all the time is likely to make you gain body fat. Moreover, eating protein-rich foods with an amino-acid profile that does not match the amino-acid profile of skeletal muscle is not a good strategy:

http://healthcorrelator.blogspot.com/2010/11/amino-acids-in-skeletal-muscle-are.html

Meat and eggs are good choices. Protein supplements are not as good.

Liver and muscle glycogen should also be replenished. A combination of fructose and glucose is ideal for that:

http://healthcorrelator.blogspot.com/2010/06/fructose-in-fruits-is-good-for-you.html

Liver glycogen is replenished in hours, while muscle glycogen is replenished over days. When glycogen stores are low, more fat is oxidized and some muscle protein is used for glucose generation by the body. Glucose is needed primarily by the brain and red blood cells. Because of that, both carbohydrates and fat are effective at sparing muscle.

If your hunger regulation is working well, you should feel hungry for the right nutrients at the right times. Sometimes it takes a long period (e.g., 1 year or more) to "fix" hunger regulation mechanisms after a long period on a Westernized diet, which is great at messing them up.

I trust my body more than fitday, conventional calorie charts etc. If your systems aren't broken, I.e. Leptin/insulin resistance then yes. Friggen eat. If your hungry every 3 hours, your doing it wrong, up your per meal calories, up your fat, and limit your carbs to post workout

Eat more if hungry, not necc more often.