I did that a few times - not in one sitting but just eating pie as my only food for a couple days (I’m not a big eater). I remember standing in line at Albertson’s in my early 20s, seeing a rack of peach pies and suddenly realizing I could just buy one for myself. I was an adult. I could get a whole pie and eat as much of it as I wanted. Another time I ate almost nothing but Cap’n Crunch all weekend. A friend of mine had a summer job at a pizza place where she got to take home one pizza per day. She put them in her freezer and lived on pizza all summer, zero grocery expenses.