Isn't a standard alternative, you can push a very fat man on the track and derail the trolley. All of a sudden a lot less people are willing to sacrifice the fat man.
Despite the fact that a man fat enough to derail a trolley, if even possible, likely has an extremely low quality of life and an extremely short life expectancy.
Not to mention, unless you’re into bodybuilding, trying to push anyone who weighs enough to derail a trolley will probably not work.