Without a belt my pants fall down. Simple fact for my middle aged body type. BUT, I have found a solution. I actually wear invisaspenders They are a suspenders that you wear under your tucked in shirt. Sounds bizzare.. but they actually work.
Home - The Amazing Invisible Suspenders! (Website seems to have fallen into dis-use, but you can order on amazon.)
https://www.amazon.com/Invisaspender...invisaspenders