Originally Posted by memphis2012
from the sounds of it, you're metabolism is thru the roof. you could try weight gainers and working out, but you're only 20 so your body will probably burn everything off. you might have to go for a good 8 meals and maybe something upwards of 6 grams of protein per pound of body weight, but be careful with all that protein and take milk thistle. it's easy to manipulate your body, but it's something unique, so be careful with just doing what everyone else says or does, a visit to a nutritionist will help pinpoint your exact diet.
Do NOT eat 6 grams of protein a day per pound of body weight, that is very, very unhealthy. The stress is on the kidneys, which has to excrete the waste products from protein breakdown (creatinine and urea) which is what worries people. I'm fairly certain there is no stress on the liver from increased protein intake. I was in your same boat a couple years ago, but have been steadily gaining weight by lifting heavy and eating a lot. Balanced diet is the way to go, with an emphasis on protein. I try to always have something to eat about every 2 hours, not a full meal, but maybe a banana or a protein bar or peanut butter with something. Like others said, you have to intake more calories than you expend, which is difficult with a high metabolism. Eat a lot of good food is my best advice and peanut butter is a great way to get extra calories in for the day.