$4.15 billion of new commitments were made to tackle hunger at a June 2013 Hunger Summit held in London, hosted by the governments of Britain and Brazil, together with The Childrens Investment Fund Foundation.Despite the hardship caused by the 2007–2009 financial crisis and global increases in food prices that occurred around the same time, the UNs global statistics show it was followed by close to year on year reductions in the numbers suffering from hunger around the world. By 2019 however, evidence had mounted that this progress seemed to have gone into reverse over the last four years. The numbers suffering from hunger had risen both in absolute terms and very slightly even as a percentage of the worlds population.In 2019, FAO its annual edition of The State of Food and Agriculture which asserted that food loss and waste has potential effects on food security and nutrition through changes in the four dimensions of food security: food availability, access, utilization and stability. However, the links between food loss and waste reduction and food security are complex, and positive outcomes are not always certain. Reaching acceptable levels of food security and nutrition inevitably implies certain levels of food loss and waste. Maintaining buffers to ensure food stability requires a certain amount of food to be lost or wasted. At the same time, ensuring food safety involves discarding unsafe food, which then is counted as lost or wasted, while higher-quality diets tend to include more highly perishable foods.
Definition and related terms
There is one globally recognized approach for defining and measuring hunger generally used by those studying or working to relieve hunger as a social problem. This is the United Nations FAO measurement, which is typically referred to as chronic undernourishment (or in older publications, as food deprivation, chronic hunger, or just plain hunger.) For the FAO:

Hunger or chronic undernourishment exists when "caloric intake is below the minimum dietary energy requirement (MDER). The MDER is the amount of energy needed to perform light activity and to maintain a minimum acceptable weight for attained height." The FAO use different MDER thresholds for different countries, due to variations in climate and cultural factors. Typically a yearly "balance sheet" approach is used, with the minimum dietary energy requirement tallied against the estimated total calories consumed over the year. The FAO definitions differentiate hunger from malnutrition and food insecurity:
Malnutrition results from  "deficiencies, excesses or imbalances in the consumption of macro- and/or micro-nutrients." In the FAO definition, all hungry people suffer from malnutrition, but people who are malnourished may not be hungry. They may get sufficient raw calories to avoid hunger but lack essential micronutrients, or they may even consume an excess of raw calories and hence suffer from obesity. Food insecurity occurs when people are at risk, or worried about, not being able to meet their preferences for food, including in terms of raw calories and nutritional value.