Google - Why can't I gain weight? Im 6'0 tall 20 years old and only 130 lbs, I've been zerging food?

Try focusing on a low carb, high protein diet, between 70 and 100 carbs per day, and weight training, in your case you shouldn't do too much cardio exercises but you should still do some. You need to focus on gaining muscle mass more than just gaining weight.

I'm not a professional so you should still see a dietitian about your problems.