Lecturers, as well as students and guests, have the possibility to visit the different dining-halls and cafeterias of the university. There people can get reasonably priced meals with vegetarian and sometimes vegan options as well as a salad buffet and a variety of hot and cold drinks.
You can find the weekly changing menues on the websites of the Studentenwerk.
Additionally there are several super markets, restaurants, cafés, snack bars, etc. close to the university.