The hormones can trigger hunger or cravings, but you can choose to give in or not.
That said, personally I have tried Depo injections and some type of pill. When I am not on BC I crave bacon cheeseburgers and brownies for about 5 days a month, on Depo it is about 3-7 days every 3 months right before the next injection is due, on the pill I craved them 2-3 weeks a month. When I gave in I gained, when I didn't I was miserable. Because of all this I ended up gaining on the pill and losing on depo.
it is always worth trying different things until you find one that works for you. I'd say give implanon another shot and pay attention to how it effects you for a few months, as long as you don't mind whatever effects it has then keep with it, if you don't then try something else