Is evolution beginning to favor the less fit?

BBC – Earth News.
Live fast, die young? Since 1859 when Darwin introduced his work On the Origin of Species, the ‘theory’ of evolution and natural selection has been widely accepted among scientists.  I remember being taught about evolution in school and thinking the data was convincing because it made so much sense.  Of course evolution would favor the stronger, faster and more fit – they could out run, out fight, out think their competition.  So, as I was reading today’s BBCs article, I couldn’t help but wonder if times have truly changed.  The study referenced in the article showed that snails with slower metabolism grew bigger, reproduced more and lived longer.  It stands to reason that those same snails actually move slower which is next up for the same research team.  Obviously human beings are much further evolved than the common slug but someday, will slower, bigger (re: fatter) people actually have a longer life expectancy?  Will the morbidly obese, someday be considered the fittest?
Our society already caters to this population in many ways encouraging an inactive lifestyle.  Hopefully evolution will not follow the same trend, but if it does, we can all take a little solace in the fact that evolution moves at a snails pace and that pace is slowing down.