“Pepsi”
Any chance you could get your father-in-law interested in “Diet” or “Zero Sugar” drinks as a kind of intermediate step? They’re tasty. Artificial sweeteners can be problematic though, in that they can get us craving sweets at other times. My health and weight improved years ago when I gave up sugary drinks. When at times I have given up even the diet drinks and switched to mostly only water, my weight improves even more. Seen so many people drop weight when they get what they drink correct. Not the full story but quite a start. At least see if you can get him to give up caffeine in soft drinks. Can be a couple or three unpleasant days when going off sugary soft drinks, maybe stomach upset. But worth it. I try to use Lent to get my appetites under control. I don’t care much for vegetables either but if they’re a part of something I like, like beef stew, will eat them.
Unfortunately, they don’t give him they same taste and feel. I think there can be an aspect of getting energy from the carbs that makes one think this extra energy is “fixing” something.
He has little ability to check his desires when it comes to food. He has a limited list of things he enjoys, and practically none of items on that list are “healthy,” unless snack cakes changed food categories in the last few days.