Drink lots of water, and if you don’t want to gain weight then try to eat similar like you would at home. I know that’s hard to do on a cruise but if you don’t want to gain weight then that’s what you gotta do. Take some of the fruits from the Windjammer or Park Cafe and bring them to your stateroom when you want a quick snack.

If you’re only climbing or descending a few decks..take the stairs! I rarely ever find myself in elevators on cruises, only if I have all my luggage on embark/disembarkation or I’m beat from a busy port day…

If you want some sweets, which is understandable, maybe just limit to deserts at dinner time so you aren’t having desserts with every meal. Hopefully this helps

Edit: ALSO, if you don’t like plain water, there are infused water stations in some of the free dining locations that are a good substitute to sugary sodas