My dentist told me to eat a lot before my wisdom teeth extraction. why?

Helps healing: He wants you to be well nourished to help with the healing process. If you are mal-nourished, it takes much longer for you to heal after the surgery.

Not typically: Usually we tell patients to eat light prior to surgery. If you have IV sedation you can't eat for at least 6 hrs before. My guess is that he\she was being somewhat comical. Some patients are too sore ; swollen for a period of time after wisdom tooth removal (especially the more difficult ones), to be able to eat normally. Perhaps he\she thought you are a chipmunk ; have to store your food 4 winter.

Wisdom tooth removal: Your mouth will be sore following extraction of your wisdom teeth, so perhaps this is his way of warning you to be prepared not to eat. If you are having sedation then you should not eat before your appointment. Best to clarify this with your dentist before your appointment.