Hi, I am 5'8 and weight around 125 lbs and i was wondering if nutrition is any different for someone underweight on a workout program to gain weight and build mass rather than someone whos overweight on a workout program trying to build muscle and lose fat. I know the major difference is that for someone underweight, the main goal is to put on weight and therefore eat more calories rather than less for someone who is overweight. But im curious if any of you have any input on exactly what is the best way to approach this problem in nutrition for someone underweight. How much extra calories do i need to intake above my normal daily amount? and what % of proteins, carbs, fat do i intake? I am currently taking whey protein supplement to help with post workout, some of my friends suggested taking a weight gainer, but i didnt see the need since its just more protein in a weight gainer and i could take 2 servings of whey or just go with a protein shake blend along with whey or just increase my daily calorie intake. Please if you have any suggestions, let me know. Thanks!

From my experience everyone is different. I have trainned with quite a few people with ultra high metabolisms (as in they eat twice as much as me and still are thinner than me). You need to get your nutrition down. A few people when bulking eat whatever they find, but if you are looking to keep fat off its best to do what is refered to as a clean bulk. This is where you eat clean foods i.e complex carbs, protein and good fats(peanut butter, olive oil and fish oils) and avoid sugar and generally junk. Ofcourse you should work out your maintanance which is about 14 times you weight. Then from there I would increase my intake by another 500 cals and wait a couple of weeks and see if you are putting on any weight. If no then up it by another 500. So on until you see yourself putting on weight, then keep it steady. You should keep an eye on bf and if you notice that your bf is on the up and up lower cals again by 300. If you stop gaining weight up it again by say 100. You see its a balancing act you basically need to listen to your body and dont forget as you put on weight so does your calorie intake change.
This is by no means full proof and I am no specialist the best person to consult would be Jeremy and some others on the board whose names elude me. Above all you need determination, not the kind that will burn britely for a week but the one that burns slowly and steadily over time.
Good luck!

125lbs isn't much for a guy your height. But. Is this mainly because you have extremely low bodyfat (7-5%) or because you have very little muscle mass?

My guess would be a combination of the two, so what you would need is a workout regimen that let you build lean mass, and a diet that allows your body to grow. Simply put a good bulking diet.

I don't know you, but I guess a healthy goal would be to put on maybe 10lbs lean mass and 10lbs fat in, say, 6-8 months? (or whatever fat poundage that brings you to 9-12% bodyfat.)

To get "everything right" when it comes to nutrition, I'd actually recommend that you check out www.dietpower.com. I'm using it for ripping right now, but it can without any probs be used for bulking as well.

In DietPower, you log what you eat, for how long and what you do for workout, your weight and DietPower then tracks your progress and actually calculates your metabolism - very accurately.

hmmm interesting, but i was wondering what proportion of fat vs protein vs carbs should i take in if i were to increase lets say 500-1000 calories on my diet plan per day. Thanks for the previous info.