Re: effective weight ganing food
figure out the appropriate weight range for yourself first by factoring in your height/age/gender ...
then if still underweight ... as others have said ... increase caloric intake + exercise ...
see your physician before starting on any wt gain/wt loss diet/exercise regimen for a baseline endocrine (hormones) workup ...
and most of all ...... don't give a crap about what others have to say! do the right thing for yourself ... always