My BMI is somewhere around 19 (5' 2", somewhere between 7 stone and 7.5 stone depending on whether I'm miserable or not - if I am, I can't eat). I'm 49 and in peri-menopause.
Generally, I eat very small portions. Breakfast is either a slice of toast with Marmite, or one shredded wheat. If I had both toast and cereal, I'd feel over-full for the rest of the day.
Lunch is either a sandwich (thin bread) or salady things.
Dinner can be anything, but normally involves pasta. Again, though, small portions.
I don't like chocolate, biscuits, cakes, puddings etc, but would happily eat crisps all day (I don't, though). If I do snack, it's on fruit.
I do drink a lot of a small amount of wine. Plus black tea and black coffee by the bucket-load.
I also walk everywhere and have a non-sedentary job.