I used to eat so much fat and sugar that I didn't notice when a dish I was served in a restaurant was cooked with a lot of butter/cream etc. Since cutting back I can tell when tasting it, but by then it's a bit late.
I was in France recently on business and we went for a meal with our French hosts. It ended up being 6 courses, every one of which had dairy procuct in it (local speciality). By the time the third course had come out I had decided to run with it, have some red wine as well and sort out the consequences later!!
Thankfully the weight came off quite quickly when I got back.