Jo was quite small and petite and sporty - I don't see her as being the pizza guzzling, cider swigging type, tbh unless she was planning to share it.
I think it is hard to say what type she is unless you personally know her and her habits.
I am a slim athlete and myself and many of my athletic buddies sometimes like nothing better than pigging out on the likes of pizza, burgers, fries, beer etc at the end of the week or after a long day out running, biking or whatever.