yeh European food and lifestyle are a little bit healthier than Americans (no offense I love American Food) so you'll find yourself losing some pounds as your Gf.
Remember to have fun and a little tip is to go easy on alcohol ahaha every time my relatives from New York or Canada come here they get really drunk cause they're used to drink "more" but watered down a little bit and the same quantity here it's like the triple amount of alcohol; especially when talking about beer and wine...