When I first started cruising in 2006 I believe it is, the thing that bothered me about cruising is that I will end up overeating. Seven whole days of pigging out is not good.
As the years went on, I noticed that the cruises are taking more and more into consideration the health and well-being of their guests onboard. They make sure that you are aware of their gym facilities, the walking/running path, and other outdoor sports equipments.
However, the best place I see of this changes for the better is on the food they serve. They have specialty restaurants that cater to the light and healthy diner. Also the food they serve on the main dining rooms have changed significantly in the portion sizes they give. I was always aware of the wastefulness in cruise.