You're Drinking Too Much During Your Workout
Yes, you can under and over hydrate, so finding that happy medium will help you avoid weight gain. "If you weigh yourself immediately after a run, and you're heavier than when you started, you're drinking too much water," says Jonesco. If you drink too much water, not only will your water weight seem to add pounds, but it's also potentially dangerous. "Overhydrating could dilute your blood and cause a potentially fatal condition called hyponatremia," he says.