Yes, cruises are very Bright Line Eating friendly. They almost always have a cafeteria-style food court available (sometimes all day long), and you can even bring your scale there. Generally, the chefs in the full-service dining room are all very open to being approached beforehand—just inquire what will be served, how they’ll be cooking it, and let them know you don’t eat any sugar or flour. You can also ask for extra vegetables. Several days with eyeballing three meals a day can be tough, so I would encourage you to weigh and measure some of your meals.