Just as "ridiculously rich" is relative (for some people in 3rd world countries it could be having a few thousand dollars) so is "ridiculously thin" (for someone weighing 350 pounds this could be weighing 250 pounds). And I would argue that achieving this goal, in general, leads to better health. This is not to say that exceptions which lead to poor results don't exist in both cases, which makes the correlation even stronger.