To gain 1 measley pound of fat, you would’ve havsto consume around 9500 calories Saturday, Sunday, Monday. If you don’t think you ate sub 10,000 cals in 72 hrs then you didn’t gain a single pound of fat. The scale will say you gained 3-10lbs but I guarantee you it’s water retention, you just didn’t poop yet, or both. So relax. You’ll be okay. Hop back on your normal routine and keep killing it. Water weight will fall off by peeing, breathing, and sweating.