Respected sir/mam.i am an 21 year boy i hav a severe problm of underweight.since 3 years,why i dont know.i am also a medical student.their is gradually decrease of weight & health & i feel my immune system may become weak.what the problm is with me i dont know,i have'nt a strong appetite.& If i eat or my diet is strong then also i dont know why health not growing.i am completly depressed by(society),mentally by hearing comment on me.but their is 1+ point that i do not become ill very easly & soo