This article is from the Big Folks Health FAQ, by email@example.com (Sharon Curtis) with numerous contributions by others.
For years, fat people used to be denied surgery until they lost weight.
When weight-loss surgery came along, anesthesiologists had to figure
out how to anesthetize fat people.
The problem was that common anesthetics are absorbed by fat tissue,
so a higher dose is needed to anesthetize a fat person (although
not to maintain anesthesia). Nowadays much more is known about
anesthesia for fat people and it is much safer.