I am 18 .college student .my weight is 122kg .bmi is 35.48.recently i hav gained by around 11kg.my weight gain is in my stomach which is growing very ?

No short answer: I can't guess the sex of this patient but if it is a woman I am afraid she may be pregnant. Often though when students enter college (and are a real student) they spend more time in the library & not exercising & eating well, which tends to expand abdomens. Eleven kg is not a lot & in either sex could be the fast food diet, but a woman whose stomach is "growing very", i'd get a pregnancy test.