Like I said, the types of food you mentioned above are good, but they aren't good enough. Taking 90% whey protein is the best solution to repearing muscles. You can't tell me you can get that percantage of protein in eating something like turkey, fish, cheese, etc. Sure eating meals that include the foods you mention above help, and they are healthy and pack a lot more nutrients your body can use. But you should find a balance between eating properly, but at the same time providing your body high percantage of protein so your muscles could repair at a more rapid pace.

You're right that muscle does weight more then fat and that protein does make them bigger and stronger, but to just rely on this method in gaining mass will take a very long time to note results. If he's serious about gaining mass, taking a weight gainer is the best way to go. I take one my self at the moment.

A whey protein container does not cost $100, not even close, atleast where I live. A protein container which will last you roughly around a month if taken atleast 4 times a week, which will last you no more then a month, would cost around $45.

Eat pb&j sandwiches..

Instead of resting in between your workout days, it can pay off to do different types of cardio. For example, say you work out your chest and back area one day, you should try to focus only on cardio the next. Maybe use some light weights in a few of your exercises, but nothing too extreme. I followed the routine of workout-cardio-workout-cardio-workout for five days a week (two day rest period) for about two months, and the results were pretty there.

As for eating habits, just make sure you're eating a hearty amount at every meal and try to skip snacks. Protein helps, but as long as you're eating consistently, then your metabolism should keep up with your new habits. Having a quicker metabolism always helps stuff like this. I don't know if this method is for everyone, but it surely worked for me.

Also, do abs every day you do your workouts (excluding cardio days). Abs can fit in at the end of other body parts, and they can be worked multiple times a week for results. If you want, do different ab exercises on different days. Whatever you decide to do, good luck man!

I was gonna ask about abs. How are they any different from any other muscle group, shouldn't I just let them rest as well? I mean, right now they're sore, should I let them repair themselves?

Also with cardio, that's not a good idea at the moment since I'm trying to gain weight and savor every calorie I have.

There a several types of cardio that help gain weight, too. Plyometrics, or jump exercising, can do the trick. Search online or something for useful routines. It's also very good for your heart. But I understand the sentiment of trying to put on weight.

As for abs, yes, resting them on your in-between days is definitely necessary, but since they are traditionally harder to build than other muscles, it would be fine to work them three days a week. I wouldn't do anymore than that, but if you want to see noticeable results sooner, then three days should be enough.

There are a lot of great tips for building muscle.

-First running isn't helping you with gaining muscle. Cardio from what I've read tears down your muscles. I'm not saying cardio is bad, as it's very beneficial for conditioning your body, but look at professional runners how lean they are. Cardio burns calories, and once it's burned up calories it will start to eat your muscle.

-not taking days off between exercising doesn't allow your muscles to recover. Exercising creates wear and tear on your muscles. By not giving yourself time off between workout days you don't give your muscles time to recover, and get stronger/bulk up.

-Protein is very important as well as it helps your muscles to heal. I'm a big reader of Men's Health, and they say nutrition doctors recommend eating 0.77 gram of protein per pound of body weight. Or a 180 lb man who works out regularly needs 80 grams of protein per day.