A curvy woman might wear a belt around her waist to emphasize her curves and the narrowness of her waist, to make her hips and breasts look bigger.
If you mean belts like the belts that people use to keep their pants up, I am pretty sure they can NOT be used as substitutions for for bras. I'm sure these belts you see are just fashion statements. When people wear strapless or spaghetti dresses, they probably are wearing bandeaus or strapless bras underneath. -Pink Carnation
No, it's an accessory. Either to compliment the outfit, or to show off her figure and provide more definition. Definitely not used as a bra.
I don't know what's more hilarious....
