Post on Hormesis - useful summary of the key issues by Josh Mittledorf
"Maybe the fact that overeating is bad for our longevity is so familiar to you that you no longer think it’s strange.  But believe me, it’s strange.  It’s strange that the harder you work your body the longer it lasts."
Particularly why science community ignores it still:-

• Association with the problematic science of homeopathy.  In the early 20th Century, people who promoted homeopathic medicine were prominent supporters of the concepts of hormesis.
• Polluters and chemical manufacturers seized on the idea to argue, opportunistically, that pollution is actually a boon to public health!  In fact, owners of nuclear power plants argue that leakage of radiation is not a problem as long as it is below a threshold dose*.
• The true strangeness emphasized above.  Hormesis implies that the body is unable to be fully healthy if it has all the food it needs, and is deprived of poisons and stressors.

http://joshmitteldorf.scienceblog.com/2014/12/09/what-doesnt-kill-me-makes-me-stronger/