why is this even up for discussion? Are u looking to actually do this for some reason? and there is no answer to this as others have pointed out because it depends on many factors. i mean lets say ur weight is 97 pounds at 7% bf and gained 3 pounds of pure body fat (10,500 extra calories) u would be 100 pounds at 10%. i highly doubt anyone on this board weighs this much, many are at least 200 and many weigh much more so basically 21,000 extra calories for a 200 pounder
it does matter on what ur bf level naturally is. then we need to factor in the elevated metabolism the excess cals will have on leptin and thus thyroid stimulation so an extra 3,500 cal will not necescarily make a pound of fat it might take 4-5,000 for 3,500 to be turned into fat and what nutrients u take in and the quality of them matters as well any supplements ur on are all factors
same logic applies to dieting, a 500 calorie a day deficit might lead to a pound of fat loss in the first week but overtime ur body's defense mechanisms kick in; drops in t3, leptin, etc...