Undernutrition takes the following forms:
- Wasting: UNICEF defines moderate and severe wasting as below minus two standard deviations from median weight for height of reference population. Wasting is usually the result of acute significant food shortage and/or disease.
- Chronic undernutrition – stunting: UNICEF defines moderate and severe stunting as below minus two standard deviations from median height for age of reference population. Stunting is caused by long-term insufficient nutrient intake and frequent infections.
- Micronutrient deficiencies: According to UNICEF, micronutrient deficiencies occur when people do not have access to foods rich in micronutrients like fruit, vegetables, animal products or fortified foods. This is usually because they are too expensive or unavailable locally. Micronutrient deficiencies increase the risk of infectious illness and of death from diarrhoea, measles, malaria and pneumonia and are associated with other deadly and highly debilitating diseases.
In 2016 a downward trend was observed in the number of undernourished people globally, but the Food and Agriculture Organization of the United Nations (FAO) showed that in 2017 the number increased again, with an estimated 815 million people around the world suffering from hunger every day. This reversal is the result of greaterfood insecurity caused by a higher number of conflicts, which are often aggravated by climate-related disasters. In addition, food availability and accessibility have been impaired due to slower economic growth.
While undernourished people are more prone to developing infectious diseases, undernutrition in children also affects their physical and mental growth, which in turn limits their achievements later in life. Globally, 23% of the population under five years of age is classified as stunted, of whom 94% live in Asia and Africa. Although the prevalence of stunting and wasting has decreased in many countries, progress is not on track to meet internationally set nutrition goals. For example, it is disquieting that, from 2000 to 2016, little or no progress was made in reducing stunting in Africa and Oceania. Furthermore, approximately half (45%) of the deaths of children under five globally are linked to undernutrition, a substantial proportion (12%) of which can be attributed to sub-optimal breastfeeding.