Throughout history, a large proportion of the world's population have experienced frequent severe hunger. In many cases, this resulted from food supply disruptions caused by war, plagues, or adverse weather. For the first few decades after World War II, technological progress and enhanced political cooperation suggested it might be possible to substantially reduce the number of people suffering from hunger. While progress was uneven, by 2000 the threat of extreme hunger subsided for many of the world's people.
Until 2006, the average international price of food had been largely stable for several decades. In the closing months of 2006, however, prices began to rise rapidly. By 2008, rice had more than tripled in price in some regions, and this severely affected developing countries. Food prices fell in early 2009, but rose to another record high in 2011, and have since decreased slightly. The 2008 worldwide financial crisis further increased the number of people suffering from hunger, including dramatic increases even in advanced economies such as Great Britain, the Eurozone and the United States.
The Millennium Development Goals included a commitment to a further 50% reduction in the proportion of the world's population who suffer from extreme hunger by 2015. As of 2012, this target appeared difficult to achieve, due in part to persistent inflation in food prices. However, in late 2012 the UN's Food and Agriculture Organization stated it is still possible to hit the target with sufficient effort. In 2013, the FAO estimated that 842 million people are undernourished . Malnutrition is a cause of death for more than 3.1 million children under 5 every year. UNICEF estimates 300 million children go to bed hungry each night; and that 8000 children under the age of 5 are estimated to die of malnutrition every day.
As a physical condition
The physical sensation of hunger is related to contractions of the stomach muscles. These contractions—sometimes called hunger pangs once they become severe—are believed to be triggered by high concentrations of the hormone Ghrelin. The hormones Peptide YY and Leptin can have an opposite effect on the appetite, causing the sensation of being full. Ghrelin can be released if blood sugar levels get low—a condition that can result from long periods without eating. Stomach contractions from hunger can be especially severe and painful in children and young adults.
Hunger pangs can be made worse by irregular meals. People who can't afford to eat more than once a day sometimes refuse one-off additional meals, because if they don't eat at around the same time on the next few days, they may suffer extra severe hunger pangs. Older people may feel less violent stomach contractions when they get hungry, but still suffer the secondary effects resulting from low food intake: these include weakness, irritability and decreased concentration. Prolonged lack of adequate nutrition also causes increased susceptibility to disease and reduced ability for the body to self heal.
Malnutrition, famine, starvation, appetite
Malnutrition is a general term for a condition caused by inadequate dietary intake and/or disease; it can occur in conjunction with both under and over consumption of calories and/or micronutrients.
Famine is a widespread scarcity of food that may apply to any fauna species; the phenomenon is usually accompanied by regional malnutrition, starvation, epidemic, and increased mortality.
Starvation describes a "state of exhaustion of the body caused by lack of food." This state may precede death.
Appetite is a natural desire to satisfy a bodily need, especially for food.
The annual FAO, WFP and IFAD The State of Food Insecurity in the World reports provide a statistical overview on hunger,