I can not find anything on the TSA website which requires that belts be removed. It does say, however, that metal belt buckles will often set off alarms.

What it my belt has no buckle at all? Do I have to remove it?

I have a belt whose buckle can be removed in an instant. It would certainly be quicker for me to remove the buckle, and put it back on after screening, than to take off the belt and then rethread it though my pants' loops.

Is there any rule against wearing only the belt without the buckle?