The best appetite suppressant is simply not to be hungry.
First thing to consider is it takes about 20 minutes for your body to realizes you have eaten food, and start to break it down. It could be that your having your meal then going straight to the cupboard because you think you're still hungry? You need a distraction, for me it's usually washing up the dishes after.
How often are you eating, are you leaving it until you're 'starving' to eat, in which case, the meal might not be enough. For me I then to eat at 10am, 2pm and 6-7pm (depending on work), and aim for 500 k/cal per meal, which leaves me room for a couple of snack if needed, in between. If I do get hungry a simple high fat/protein snack works, like peanut butter (yep, I'll just eat a couple of tablespoons of that, amazing how long that can fill you up for)
Do your meals have enough fats in them, fats keep you full for a lot longer, bacon, peanut butter, cheeses, olive oil in your salad, etc.
Finally is it just a habit, do you loiter around the kitchen for no real reason then just 'oh just have a quick snack' whilst you're in there, would doing other things distract you and break this habit?