I’ve been doing 16:8/18:6, sometimes 20:4, since the beginning of the year and lost 7.5 pounds 1/1-2/12. I was on vacation this past week and had to stop doing IF. I got back home and weighed myself and I’d shot up from 162.5 back to 167.5!!! Is it really possible I gained all that weight back in a week? :( F, 5’4”, SW 170
Is it possible you gained 5 lbs of weight in 7 days? Yes
Is it possible you gained 5 lbs of fat in 7 days? Yes, but very unlikely unless you were eating an extra 2500 calories + your maintenence tdee calories every day.
Weight gain/loss and fat gain/loss aren’t the same. Fat is fat. Weight is fat, muscle, food, glycogen, water, feces, etc. You likely lost mostly 7.5 lbs of fat since you started. You likely gained 5 lbs of weight in 7 days, but not all of it, if any, was fat.
If you drink a gallon of water, your weight temporarily goes up 8.3 pounds.
You could seriously just have more food or liquid in your system from your vacation and get a variation like that.
Try to always weigh yourself under similar circumstances. First thing in the morning after using the restroom, etc.