There might be a need to check other levels in your blood. Keep an eye on thyroid hormones which a lot of meds play with but lithium especially does. It can damage a thyroid gland and does. It did mine and I gained 90 pounds in a couple months. I'm finally, 13 years later, into a size of pants that I haven't worn in over 30 years and still need a belt.
The thing people smoke that makes them hungry only did that to me a few times but always revved me up.
Every med I take for MI has that hunger factor. For some reason, that part stopped. I still have times where I'll eat enough junk food to fill a shopping buggy, but I do try to limit those. I also use exercise. Although I sometimes do, it's a lot harder to eat while working out. Just the looks I get in the gym are enough usually to stop me from doing it. I did recently eat a soft pretzel while jogging. I heard growling, so I asked if they were hungry or wanted a bite. She accepted. I'm weird and don't worry about those things. Coffee helps too, but I try, though poorly, to limit that intake. I'm actually having a coffee now.
Water does help a little.
Whole grains and absorbent foods help tremendously, especially when eaten slowly. A granola bar is a minimum of 5 minutes meal with me usually, because I make it take that long. I like to slowly enjoy foods that I like. I eat much less and feel much more full. Mastication in general is the supposedly first indicator to the body that you're getting full.
It can be done. I do things in spite of them being the opposite of what I should do, or something like that. Find what works for you.