General

One of the easiest ways is to joke around. While you are eating, say something like "if I keep eating like this I am going to weigh 500 pounds." Get his reaction. If it is bad, you can laugh it off. You may have to tell him eventually, but at least you'll know how he feels about it.

The joking at dinner is a great idea. May be hard to judge his response. After dinner you could also say " oh I'm stuffed. I was very hungry and everything was soo good." Maybe rub your belly. If things look positive maybe unbuttoned your pants. If he's a fa you'll know. If not you just over ate.