How to tell a friend to stop eating so much?

Also posted in Etiquette- but I know that forum doesn't receive a ton of traffic.

My bf and I throw a monthly game night at our apartment with friends, but one fellow in particular eats far more than his share. He is fun for the games and close friends with some of the other attendees. It's always a bit of a potluck and everybody brings either a 6pack or a dish to share and typically it would be plenty to feed the 6-8 people usually there and then some (usually enough for everyone to get a second serving). Last time we passed a platter of appetizers from the kitchen to him, as he was closest, to share with the table- he ate it all himself! When preparing/plating/eating food he'll stand just behind you and every now and again audibly smack his lip. Quite frankly, my dog is better behaved than this.

These are some really annoying behaviors that I want to address clearly, but gently if at all possible. I don't want him to feel unwelcome or that he shouldn't eat AT ALL when visiting. Just that there are other people to share with and eating enough for 3+ people in this setting isn't really acceptable. How should I approach this?