The bride and groom took a lot of effort to invite you and to design/plan their wedding for you to attend. The least you can do is the give a good gift, at least enough to cover you and your guests meal/drinks. Your generosity will not go unnoticed.
When you travel, don’t worry about your diet. You’re not going to be on your death bed saying,”oh I wish I had just eaten that salad and plate of vegetables when I was in Florence.”
You’re going to say, “thank god, that I stuffed my face with nutella pies, meats, and cheeses when I was in Florence.”