I don't think I gained that much weight on my cruise (7Lbs+ or 3.18Kg+). But I am sure I gained a few pounds of weight on my cruise>
The culprit in my case was drinking lots of soda to justify the purchase of the Soda Fountain Card.
Fortunately, all that walking around the ship and using the stairways, moderates my weight gain. Of course, there is always the gym onboard
. Maybe someday on my future cruise I will have my first work-out at sea.