I work at a hospital serving food to patients. I only work part-time but I go to school full time. I know you said that you would have to work 11:30-8 and every other weekend you have to work 13 hours. (which is really weird..) Do you know if they will be flexible with your schedule? The hospital I work at is really flexible with school schedules. Every other weekend isn't THAT bad.
I have to work every weekend which really sucks.
I have to say it is easy work, but you will see a lot of stuff that you probably will not want to see, and be around a lot people that you have NO idea what they have. I personally have delivered trays to two dead people and didn't know they had passed, and I've had to be tested for TB because there was a patient that had it and somehow noone knew about it. But then again, every hospital is different, so you may not deal with the same stuff I do.
Oh and another thing, will you be going to school for something in health care? Even though you would be working with dietary, you still meet a lot of people from different fields and can learn A LOT. That is one good thing.
Education should really be your priority, so I would go with something that will be better for you while you're in school.