What time and place are you talking about? Different people in different cultures, to this day, eat different things at different times depending on traditions and circumstances.

It's not exactly the answer to your question, but I did address the history of breakfast in Britain here. Mealtimes did shift a bit in the 19th century, at least in Britain, to a more breakfast-lunch (or luncheon)-dinner pattern. But, supper was and remains common, and having "lunch" at midday rather than "dinner" as the main midday meal still to some extent breaks down along class lines.