Low water.
High water will just get rid of all the water, rendering the High Sodium/Carbs completely useless.
It's both...What I would do in his situation (I don't know how much time he has so lets say a week).
I'd pound carbs and sodium a good source would be asian food and rice. for the first 4 days my water would be high to maximize the amount of water weight and last 3 days would be low...If you only had a couple days then yes, low water.
You wouldn't use low water for a week you could gain much more using high water then cutting back but you have to eat alot of carbs and sodium.