Why is it not good to touch metal, water and food after asana practice?

Asanas (yoga postures are not merely physical exercises but a special practice designed to help maintain the health and vitality of the physical, astral (luminous), ethereal, mental and causal (spiritual) layers of the energy bundle we commonly call a human being.

One of the effects of asanas on our physical body is the activation of glands, both endocrine and exocrine. The exocrine glands are situated all over the surface of the skin, the mucous membrane of mouth, the GI-tract, the genitalia, etc. When these exocrine glands become active, thousands of small pores in our skin open. They start to secrete an oily substance that makes our skin smooth and lustrous (a kind of protective layer for the skin). If we wash after asanas, the water enters the open pores of the skin. This in turn causes the pores to close immediately and affects the autonomic nervous system all over our body. It produces a kind of irritation reaction that not only affects the skin but the internal organs as well. This significantly disturbs prana (vital energy), may contribute to vata derangement, and may cause heart palpitation, rise in blood pressure, decrease in digestive fluids, etc. The wetness of foods causes a similar reaction to take place in our mouth if we eat them or on the skin if we touch them.

In addition, asanas help strengthen the ethereal and astral (aural) layers of the body. After the usual activities of the day (work, talk, stress), our aura is weakened and scattered. After the practice of asanas, however, it becomes more organized and healthy. During asanas, small pores open throughout our luminous body, which help invigorate the stream of the bio-magnetic "fluid" of our aura. This substance is obviously of electric nature and it can run through metal wires. (Magnets or metal objects noticeably affect our aura, as shown by Kirlian photography.) If we touch a metal object after asanas, our aura gets drained (earthed). The bio-magnetic fluid escapes from the body through that conductive object. Therefore, it is not good even to walk on the stone floor or on the ground with bare feet after asanas. Asanas should be done on a blanket or a mat that is of non-conductive nature.

You should wait at least 15 minutes before touching metal, water, and food after asana practice. It would be much better if you wait 30 or 45 minutes. Use this time for inspirational reading (svadhyaya).