Maintenance is easy. It’s all about understanding how to prevent lipogenic readaptation. Lipogenic readaptation requires the refilling of glycogen stores. You can easily prevent this by avoiding chronic Carb intake, such as setting a daily amount of carbs, which always seem to creep upwards.
The strategy I have used for years is that whenever I eat carbs, for whatever duration, I go double the time afterwards without them. If I have a heavy Carb meal, I skip them for two more. If it’s a day, then no carbs for a couple of days. Even if I eat carbs for a week, after three or four days of not eating them my glycogen depletes and I’m back to normal.
Eating carbs does cause swings in water weight. It’s really nothing to worry about, and can flux up and down quite a bit.