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.
Winter swimming
Hypothermia poses a smaller risk. According to Tucker and Dugas, it takes more than approximately 30 minutes even in 0 °C water until the body temperature drops low enough for hypothermia to occur. Many people would probably be able to survive for almost an hour. There is no consensus on these figures however; according to different estimates a person can survive for 45 minutes in 0.3 °C water, but exhaustion or unconsciousness is expected to occur within 15 minutes. Consuming alcohol before winter swimming should be avoided because it speeds the onset and progression of hypothermia.