I think it could be possible because depending on how long you went, you be in starvation and may need to rehydrate which alone can put lbs on in water, but the thing is is that usually the first couple pounds we lose are usually from water not fat. My understanding is that many have a big drop in water weight the first week or so. But that doesn't mean you can't pick up and push right past that, with clean eating, hydrating and exercise.
Vegetarian, counting calories. Loving Amazing Grace <3