No assumptions need to be revised.

Don't know about yours, but my bathroom scale isn't the balance beam type.  And thanks for the basic physics primer, but you'll note I never used the term 'weight'.  

And to make it clearer...my first post suggested that my apparent weight increase was due to the increasing for of gravity rather than Twinkies.  Then I corrected that to reflect that local gravity acting on me was actually decreasing based on the article, so I can't blame gravity for my increasing weight, and in fact if gravity had remained constant, I would even weigh more.