I think those bars are an additional form of entertainment. Having said that, I am in the same boat as you in terms of finishing food for my wife and in my case my daughter as well. I think that is the reason for my weight gain especially on vacations 😀

We do try to account for this by ordering less for me, but still we mostly fail 🙃 I was also in the same category as you most of my life even when I had 8% body fat. BMI really doesn't account for muscle.