Reason:  Let's first define 'energy efficient as; "using a low amount of energy or calories."  In terms of using the least amount of energy and staying alive, it would be hard to beat Milarepa's record.  It would not be too far-fetched to say he attained a 'suspended animation' and/or a 'hibernation' of sorts.

Granted, there have been others who have adhered to extreme ascetic lifestyles - including fasting for prolonged periods, and using no resources - but it would be interesting to know whether any real person has ever maintained an extreme ascetic lifestyle longer that Milarepa's (5 years) and survived.

For the sake of comparison, there is another type of contender; people who have become comatose for extended periods.  That's a more recent phenomena (in ancient times, they would probably have been  killed, rather than sustained in a vegetative state) - and therefore the comatose person would be tube-fed and provided comfort - all of which involves resources, and therefore detracts from being truly 'energy efficient.'

Of course, the term 'energy efficient' didn't exist in Milarepa's time (900 years ago), and even if it had, he wouldn't have been concerned about setting any records in that regard.  Milarepa's stated goal, from which he never wavered, was to attain complete spiritual enlightenment in his lifetime.  In the pursuit of that, he never wavered from doing the things that would lead, as directly as possible, to that attainment.  In doing so, he barely ate for years on end, and he used no man-made resources (other than one threadbare cotton cloth that was given to him), not even candles.  After prolonged seclusion within one or another of his walled in caves, he decided to splurge a bit, and allowed himself the luxury of heating water in a clay pot - within which he would scald wild stinging nettle leaves that he found nearby.  So the resources to make that clay pot, the small fires made of twigs, and a ready supply of wild nettle leaves comprised, for several years, his only energy usage.  A hedgehog making a shelter of twigs probably uses about the same amount of resources as Milarepa did at that time.

The story of Milarepa's life talks volumes more that the small matter of 'energy efficiency,' but it's perhaps interesting - that an objective focus on that narrow perspective will show that Milarepa, had to have been the world's most energy efficient person.

Life Story of Milarepa      
available as E-book or Audio book, see below........

	Complete E-Book    $9    ISBN 978-1-879338-00-5 51 pages in adobe .pdf  format                peruse the first chapter free
	Audio book on CD      $15        ISBN 978-1-879338-01-2     Ten chapters comprising nearly four hours   |||  .mp3 format on CD                                click here for 5 minute audio intro

Milarepa home page                      other Adventure1 Publications            author's email: Ken [at} adventure1.com