No matter what you are wearing, no matter how provocative or revealing your outfit....Silky, clingy, form fitting etc.
No matter what color it is, no matter how well it matches your complexion, eyes, or hair color....
If your belly sticks out farther than your boobs, yer not sexy, period.
Few of us are underweight in this country, but if your spare tire's circumference exceeds that of your chest, it ain't sexy. If it is double the circumference, you are obese. Some men like "curvy" girls, but fat is fat.
We guys don't expect you to have a flat belly like a supermodel, but seriously, drop the self delusion.
Look at yourself.