Human
In general, humans can survive for two to eight weeks without food, depending on stored body fat. Survival without water is usually limited to three or four days. About 36 million humans die every year from causes directly or indirectly related to starvation. Childhood malnutrition is also common and contributes to the global burden of disease. However global food distribution is not even, and obesity among some human populations has increased rapidly, leading to health complications and increased mortality in some developed, and a few developing countries. Worldwide over one billion people are obese, while in the United States 35% of people are obese, leading to this being described as an "obesity epidemic." Obesity is caused by consuming more calories than are expended, so excessive weight gain is usually caused by an energy-dense diet.
Elixir of life
In the eight-century "Man'yōshū", 'waters of rejuvenation' (, ) are said to be in the possession of the moon god Tsukuyomi. Similarities have been noted with a folktale from the Ryukyu Islands, in which the moon god decides to give man the water of life (), and serpents the water of death (sïnimizï). However, the person entrusted with carrying the pails down to Earth gets tired and takes a break, and a serpent bathes in the water of life, rendering it unusable. This is said to be why serpents can rejuvenate themselves each year by shedding their skin while men are doomed to die.