I've noticed this too as mine get older. Used to be I could count on a few extra bites when getting takeaways or eating out. Now all that's left are empty wrappers :(
I'm still a kid at heart. When my wife makes me a stack of pikelets that are supposed to last a week, then leaves them on the kitchen bench, where I walk past often during the day. I do not know where they go, but they are usually gone within a day, 2 at most!!! (must be the dog)