You can talk to him about equipment, but if he is resistant he needs to learn it the way most of us do by carrying it up a mountain. To be honest, 40 lbs doesn't seem that bad as a starting point. I've seen a lot worse. No bluejeans? No canned food?

I don't think it is realistic to plan an extended hike as a first hike. As the post above me suggested, plan a one or two nighter out and back. See how far up the mountain he can get and let him figure out his own equipment. Maybe he is a goat and will out hike you with three times the weight.