When you get the munchies if you don't already have something low-cal/fat handy, you are going to grab the first thing that
is handy. For some people (me) not eating in the evening is misery.
Cook a whole cabbage, or a whole bunch of broccolli or a whole head of caulliflower or a whole bag of carrots or a large pot of greens (no drippings

or squash, zucchini etc. Add onions, garlic, mushrooms, celery, peppers, any low/non-caloric seasonings that you like in other foods. When you
have to eat, go nuts. Eat the whole pot if you want with no consequences (except maybe a bit of gas

). By using your favorite seasonings you can head off cravings and the inconsequential calories let you eat until stuffed if you want.
Other great snack ideas are whole dills and pickled okra. Those tend to satisfy my cravings for salty/crunchy.