My sodium intake makes me balloon! If I have fries or pasta with parm or mashed potatoes with salt, etc , it's not uncommon for me to be 5 lbs up. I like hiddenstar's idea of consistency. If you always have, for example, 2000 mg of salt, who cares what MFP says. Extra salty foods will make you spike for sure.
I'd say just keep an eye on it. If you bloat one day, you can know it's just water and not beat yourself up
