Depending on your accommodation in a shared student apartment, a private room witha Kassel familiy, or a student dormitory you will have to take care of your meals and food supplies.
Most students take care of the breakfast by themselves. For the lunches, students use the university mensa facilities with inexpensive meals of good quality. See: https://www.studentenwerk-kassel.de/en/content/essenundtrinken/
You will find the student mensa of the Kassel Art School located at the scenic Karlsaue Park within a 10 min walking distance from the Institute of Sports and Sport Science.
For the dinners, again, students prepare their own meals.