[rndgermandude]

Speaking as another German, fast food is used synonymously with "junk food" here, referring to either fast and unhealthy food (burgers, fries, "fish and ships" in the UK, Currywurst, everything greasy/fatty, etc), or food with large amounts of problematic additives, or fast and low quality stuff.

E.g. there is a tiny Vietnamese place around here that's very fast, but also very tasty, very fresh and reasonably priced (6-10 EUR). They are fast as "fast food", but lack the other "qualities" of junk food, so nobody around here would refer to them as fast food.

Döner (kebab) shops are somewhere in the middle. They offer unhealthy stuff (tons of - depending on the shop, low grade - kebab meat on a Döner for example) as well as a range of veggies and less greasy meals.