My Tummy Is Big. Iam Otherwise Slim .I Suffer From

my tummy is big. Iam otherwise slim .I suffer from hypertension, but is under control with medication.I am 73 and i have a sedentary lifestyle. I HAVE ENLARGED PROSTATE and take medication. I am ok for it.Other than the size, my tummy does not give me any problem. I try to take brisk walk for an hour for six days in a week.What sort of tests can I undergo to find out if I have any disease that is causing my tummy to be big.