Every now and then I get asked "What did they eat for breakfast in the middle ages?"
The current collective wisdom on this gives the answer of, "They didn't eat breakfast," along with side comments like "Only the elderly and infirm ate breakfast, so eating breakfast was seen as a sign of weakness," ... "The church felt it was an excessive practice and discouraged it," ... and "The meal being referred to as breakfast was actually lunch."
The more I read on this though, the more it looks like the "They didn't" answer is overly simplified. I've come across a number of references in various medieval sources that are clear descriptions of a morning meal.
For example, in the story of Sir Gawain and the Green Knight (late 14th century England) there is the following text:
Full early, ere daylight, the folk rose up; the guests who would depart called their grooms and they made them ready, and saddled the steeds, tightened up the girths, and trussed up their mails. The knights, all arrayed for riding, leapt up lightly, and took their bridles, and each rode his way as pleased him best.
The lord of the land was not the last. Ready for the chase, with many of his men, he ate a sop hastily when he had heard Mass, and then with blast of the bugle fared forth to the field. He and his nobles were to horse ere daylight glimmered upon the earth.
So the lord of the land got up before sunrise, heard mass, and had a light meal of a sop (which in medieval recipes usually refers to a thin soup with a piece of bread in it).
Other sources throughout the middle ages, and up through the 16th century, specifically mention breakfast. The foods specified typically include bread, broth, meat or fish, and either ale or wine.
There are supposed to be some good papers on the subject published by accepted authorities on medieval history, but I still haven't found them. My suspicion is that there was little consistency across Europe (or across England for that matter) and throughout the whole of the medieval period, which would mean that the proper answer to the question "What did they eat for breakfast in the middle ages?" is "It depends on where and when."
I'll keep digging into the matter and see what I find.