this is a big problem for me since I'm a compulsive overeater and have been since I was a kid.
basically, if I can hear, see, smell or even talk about food, I WANT IT!
don't even have to be hungry to eat it and I have, on several occasions, made myself sick (i.e. puking) from overeating, only to start snacking about 10 minutes later.
best thing I've done (and it's a challenge sometimes) is set a timer on my phone to ring every 2 hours to allow me to snack for about 10 minutes. but I have to remind myself to eat slowly (I'm used to shoveling food down my gullet only chewing about 4 times). So now I concentrate on taking smaller bites and chewing at least 20 times.
It's still a challenge esp when I go out with a group for a meal and food is all around me. Thankfully, most of my friends know of my problem and will move the plates away from me or I'll tell them (wait staff or friends) to move the plates out of way.