You lose more weight by sleeping than staying inactive (and watching the TV), but too much sleep is injurious to health and it is therefore not a means to consider if you want to lose weight.
Yes, we consume calories while sleeping and we consumes more than sitting watching television, or being inactive, this is the result of a study published in the Obesity Review journal.
But however, other studies have shown that increased sleep was detrimental to health, including diabetes. So to sleep or prolonged naps does not seem to be the solution to lose weight.
It was an ad on the front of hostels in old times. He was asked to travelers who wanted to take a room, to also take a meal. Weary travelers, eager to go to bed could do without meals, a shortfall but most importantly, the post office had an obligation to provide bed so no income in itself.
Under this interpretation, therefore, nothing to do with any property of sleep!
The saying can also come from a quote from Greek philosopher Menander: "Sleep nourishes the one who does not eat." This source has the advantage of seniority!
All this does not prevent to wake up with the munchies... In this case, it is mainly a way to forget a time we have nothing in the stomach.
Sleep and health
Sleep is essential, and a shortage may severely affect the metabolism. However, too much sleep can also be detrimental.
Food and sleep
Some food help to sleep.