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.
Prahlad Jani
After fifteen days of observation during which he reportedly did not eat, drink or go to the toilet, all medical tests on Jani were reported as normal and researchers described him as being in better health than someone half his age. The doctors reported that although the amount of liquid in Jani's bladder fluctuated and that Jani appeared "able to generate urine in his bladder", he did not pass urine. Based on Jani's reported levels of leptin and ghrelin, two appetite-related hormones, DRDO researchers posited that Jani may be demonstrating an extreme form of adaptation to starvation and water restriction. DIPAS stated in 2010 that further studies were planned, including investigations into how metabolic waste material is eliminated from Jani's body, from where he gets his energy for sustenance, and how he maintains his hydration status.