I've dated 0s and 00s and have had burritos with them. In my experience, no one would call them pregnant. My sister is a size 2 at most, at most stores probably a 0 (post-baby, by the way), she had never looked pregnant until she actually was pregnant. A burrito doesn't make you look pregnant, it may swell up your belly a little, but it won't make you look pregnant. Being 165lbs at 5'1" will, though...