You can't "break your body" because you're fasting. Your body sometimes just needs time to catch up to what you are doing. It's no secret that people who are calorie restricting often experience plateaus in weeks 2-3. It's an equilibrium thing all things being equal: water, fecal matter, food intake, whatever, coupled with physiological processes adapting to decreased energy intake.
It's impossible to gain fat weight on a fast and any H2O weight will be temporary.