Kolata's response is: (a) when you start drifting towards your floor weight your body automatically slows down its metabolism and (b) sends out hormones and chemicals to make you eat more. Similarly for the ceiling. It's an [almost] utterly fatalistic/deterministic argument backed up with anecdotes about how this or that person was surprised to find that they did not lose weight despite a workout regimen because they had increased their intake unknowingly. The only response I have to this sort of thing is: Duh! ;-) As I said before, and Jerry pointed out in his response, the basic argument is not new and is a productive one, but the way she puts it is far too absolutist.
--ravi