I don't think that's the case. There's more to weight regulation than "calories in-calories out", IMO. Not just water weight, either. I think there's other pathways for metabolizing fat in people, especially obese people. And I think that trumps the TDEE - caloric intake.
im going to try it, anyway. Yesterday I did spuds, but added tomato sauce and Parmesan cheese. Today, I'm going to start nothing but spuds, water and black coffee until the deadline. No exercise, except increasing my NEAT activities (high five Chaka) and I think I can hit 25 lbs. by the deadline. No bets, I just want to see how far I can go, completely eliminating everything but potatoes.