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.
Nirjala Ekadashi
While on other ekadashis abstinence of food is observed, on Nirjala Ekadashi, an absolute fast is observed, without partaking even water. The water-less fast is considered extremely difficult to follow as the day falls in the hot Indian summer and thus, it is deemed as very pious austerity. The fast is observed 24 hours from sunrise on Nirjala Ekadashi to sunrise the next day. Some observe it from sunrise to sunset. On the day before Nirjala Ekadashi, the devotee performs the evening prayer (Sandhyavandanam) and takes only one meal, without rice - as rice eating is prohibited. The devotee is however permitted to have a single tiny drop of water as part of the "Achamana" purification ritual. Water more than that equals breaking the vow.