I remember reading about a study where one group was given free access to sugary soda, and the other group given free access to diet soda. The sugary-soda group didn't drink as much, presumably because their bodies' cravings for sugar were actually being satisfied, whereas the diet soda didn't help with the cravings. So curbing a craving is definitely not as easy as just gobbling large quantities of low-calorie stuff.
Some people find that small quantities of high-calorie food, eaten slowly, satisfy cravings better than large physically-filling quantities of fruit or other low-cal foods. Your body chemistry has a chance to register and feed back that you've been eating what it is that you're craving, so you feel satisfied with a small amount.
Or, keep an eye out for healthy snacks that do work for you. My favourite is edamame (vegetable-grade soybeans in pods -- apparently a popular bar snack in Japan). You boil them in lightly salted water and suck the little beans out of the pods. This is the most satisfying snack food I have ever eaten, no lie, and I think it has to do with the combination of (a) nourishing food and (b) the busywork involved in eating them.
The other thing is, if you think it's a mental block that happens when you reach 200 lb., can you continue on your diet/exercise plan without looking at the scale as often? If you look at it every day, you'll notice when you hit 200. If you look at it every week instead, or every two weeks, will you 'miss' the magic number, or will you get the cravings without actually knowing you've hit 200? It's worth a shot, unless you have some crucial medical reason for frequent weight monitoring.