Weight / Fat loss

The program I use measures salt and water intake, so I can only hope they factor those in.

You might just be retaining more water. Water weight will fluctuate a great deal, especially when beginning to lose weight and/or increasing your exercise. That's also something that will affect women more than men, short of filing a bug report with the designer, there's not a great deal you can do about that. Although trying to stay properly hydrated and limiting your sodium intake should help.