Here is a subject I have battled with over the summer (new to the concealed carry environment). I no longer have the narrow waist of my youth and with my IWB holsters even tho I pull them as tight as I am able, as the day wears on my trousers start to droop and I have to keep hitching them up when I stand up or as I am walking. How do you cope with this problem?
What belt are you wearing, would be my question.
Having a belt specifically made for CCW (stiffened leather, or nylon with insert, or some combination) that holds its own shape and doesn't deform under stress---this is what makes the most difference for a lot of people. It won't sag as the day goes on, it won't let the edge of the belt curl over time, nor will it stretch.
If you are already using a quality gunbelt, well, then that isn't the problem.
If you aren't, though---I bet that'll fix your problem.
For me personally, for dress belts, I'm partial to the Matrix belt by Galco, and for casual wear I like the Wilderness Tactical instructor belts. There are plenty of other good-quality gunbelts out there.