Please don't do unserious answers, or at least add a disclaimer before it and make sure the question has been answered seriously prior to that.
My question:
Is it normal using cutlery always hurts? Every single time I use knife, fork of spoon for anything else but scooping something soft, it hurts. It's been like this my entire life. Are people really in pain every time they eat without anyone speaking of it????
If you want to stand up straight and sit upright then yeah you should be engaging your abs a bit. It's not the same as sucking in your gut but it does make your belly a little smaller like you said.