Vegetables! Look at the menu online before u go, u can have chicken and steak, they will swap the chips for anything u ask. The salmon comes with green bean and you've got a massive selection on the salad cart!
The weight after PV days will even out eventually, you cant not have your veg. Your body is working over time to digest all the protein as it is, not eating the veg every other or however you choose will prob cause no end of troubles!!
You can have:
Crackerjack prawns
3 of the things off of the Harvester Combo (but u can only choose 2)
Half a spit roast chicken
All the steaks
Salmon fillet
Sea bass
You will have steady losses in cruise, dont not eat veg just because you gained after 1 day of veg
But there is so much more on the Harvester's menu that you can have, if I was going there today on a PP day Id have the Harvester combo with steak and chicken, wouldnt eat the peas or the starchy side and id order a side of grilled prawns!