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.
Sustainable living
A major factor of sustainable living involves that which no human can live without, water. Unsustainable water use has far reaching implications for humankind. Currently, humans use one-fourth of the Earth’s total fresh water in natural circulation, and over half the accessible runoff. Additionally, population growth and water demand is ever increasing. Thus, it is necessary to use available water more efficiently. In sustainable living, one can use water more sustainably through a series of simple, everyday measures. These measures involve considering indoor home appliance efficiency, outdoor water use, and daily water use awareness.