This is just something amazing. Hiran Ratan Manekji lives on Sunlight and nothing else.
Hira Ratan Manek (HRM), among others, have proven that a person can live just on solar energy for very long periods without eating any food. This has come to be known as the HRM phenomenon. The method is used for curing all kinds of psychosomatic, mental and physical illnesses as well as increasing memory power and mental strength by using sunlight. One can get rid of any kind of psychological problems, and develop confidence to face any problem in life and can overcome any kind of fear including that of death within 3 months after starting to practice this method. As a result, one will be free from mental disturbances and fear, which will result in a perfect balance of mind. If one continues to apply the proper sungazing practice for 6 months, they will be free from physical illnesses. Furthermore, after 9 months, one can eventually win a victory over hunger, which disappears by itself thereafter.
A related resource is written by Param Pujya Pandit SriRam Sharma Acharya on Surya Chiktsa Vignan in Hindi. (http://www.awgp.org/books/hindi/chikitsa/01scv.pdf)