In my (totally amateur) perception, there are three different ways to be "hungry". First is hungry for calories (blood sugar may be involved here). Second is hungry for nutrients (cravings may be at least somewhat caused by this). And third is hungry for volume - your stomach physically is empty.

Eating vegetables and whole foods helps with the second and third, and somewhat with the first. By not eating highly processed foods, your blood sugar doesn't spike and then crash. (I think of it as the difference between using coal and jet fuel to make a fire.)