You can be fit and trim in the non cycling world, then put on some Cateilli euro race cut jerseys and you're a fat sausage.
I was at REI with my wife and she said "look there is a bright biking shirt on sale and it is a large, try it on". I comply. "Is it supposed to be so tight? your nipples show". Thanks, dear. I explained to her: that is a Castelli Gabba jersey, size large is meant for a 170 lb man with a 38 chest, and I already have that jersey. "You wear that outside?". I explained further, patiently. It is cycling, you are supposed to hurt yourself, suffer, loathe your fatness unless you have none and that means none, and seek redemption by riding for three hours in cold rain. "Ooo look at those shoes"'