Clinician answer
Almost all of it is water and gut contents, not fat. GLP-1s suppress appetite and slow gastric emptying, so a paused week restores normal food volume and glycogen (which binds ~3g of water per gram). Real fat regain over 7 days would require ~10,500 excess calories. Weigh yourself again 4-5 days after resuming and the number typically drops back within 2-3 lbs of where you were.
Answered by Dr. Jane Novak, MD, MPH