In three countries, I've lived with four Germans and one half-German. They've all been interested in what I eat.
I think it's irritating, but I also think that the Continental tradition of "enjoy your meal" is annoying in general. Paying attention to somebody eating seems rude to me, an American. Not so to the European. And the Germans want to talk about it.
The Germans appear slightly annoyed, for example, when I eat potatoes in the morning. It's conspicuous to most Europeans, and apparently strange even to the Irish. But sometimes the Germans appear to be offended.
] Sometimes I feel like the German housemate is worried that one of their guests might see me cooking something that they'd have to explain that this may reflect badly upon both of us....
A guy I lived with in Seville called it "the Oregon breakfast." At that time I was doing the classic potatoes, par-baked in the microwave, cut and fried in olive oil with zucchini ("courgette" in Euro-English,) bell peppers, garlic and maybe onion. All of these were exquisite in Spain. It's delicious and nutritious but it's not a normal breakfast. It's not traditional, in any known culture.
And the Germans want to talk about it.