Dave Deutsch writes: Luke, your question about the elevators on shabbos reminds me of my army days, when after explaining the whole split hooves/cud chewing rule to my fellow Screaming Eagles (I wasn't keeping kosher, but I did not eat the flesh of the swine), they would sometimes ponder it for a moment, then exclaim triumphantly "Wait a minute, chickens don't have split hooves!" thinking that they'd figured out the flaw in the system that would bring the whole thing crashing down. Just as there was an explanation for that (different rules for poultry), there is one for your elevator conundrum.
There is a different between "using" and "making use." You may not turn on a light on shabbos, but you may enjoy the benefits of a light that is already turned on. Similarly, you may not push an elevator button, but if there is a shabbos elevator, which, prior to shabbos, is automatically set to stop on every floor, you may use it. Not all elevators, incidentally, are the same. Some elevators apply different levels of energy depending on the weight that they are carrying, in which case they can't serve as shabbos elevators because you're actually causing the energy to be expended (same principle with walking through an electronically opened automatic door on shabbos, you're not flipping a switch, but your presence is working it). From what I hear of your fluctuating weight problems, at any rate, you should probably just take the stairs.
As always, I'm happy to supplement your moral authority with the halachic authority afforded me by my Orthodox Day School education. Gut Shabbos, and if I don't communicate to you before Tuesday, have an easy fast.
