Srimad Bhagavat Gita commentary chapter 17 verse 19

 Chapter 17 verse 19 

“Austerity that is performed by those with confused notions, and which involves torturing the self or harming others, is described to be in the mode of ignorance.” 

There are yogis depicted standing on pins and needles or with very little clothing on extreme weather conditions. They might be exalted souls but present a wrong notion to society that austerities need to deny the body comforts. They don’t need to necessarily. Adi Shankara stresses “not” to emphasize on the body at all and treat it with respect and sustain it well but not accord it prime importance. Ignorant people are confused about notions of actions which either deprives themselves or actual cause harm to others while thinking they are doing something good.