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World hunger: what it is and its causes

  • Page updated onApril 7, 2026
World hunger and its causes
Text and photo: Bruno Abarca

Hunger remains one of the greatest contemporary injustices, despite there being enough food for the entire population. Hunger and malnutrition are the result of conflicts, structural inequalities, broken food systems, and political decisions that sideline social protection, health systems, and access to water and sanitation. In 2024, between 638 and 720 million people were living with chronic undernourishment, and more than 2.3 billion were experiencing food insecurity.

Those of us working in health and international cooperation must understand the clinical manifestations of hunger, alongside its multiple dimensions and causes. That is why this page addresses what hunger is, how it is measured, why it kills, and why humanitarian crises intensify it to the point of catastrophe.

What is hunger and how many people suffer from it?

It's not easy to define hunger

Those of us working in humanitarian action to combat hunger know how difficult it is to define this seemingly simple term. In fact, there are millions of documents addressing the topic of hunger, and almost none of them offer a clear definition.

In reality, this lack of conceptual clarity makes sense: any way we try to define hunger ultimately proves insufficient. If we speak of a sensation, we seem to leave aside the fact that it is an injustice. If we speak of a global health priority, we seem to lose sight of the individual and family dimension in favor of the population level. If we speak of a lack of food, we seem to leave aside critically important issues such as health services, water, or sanitation.

The only way to address the definition of hunger is by embracing its full complexity and multiple dimensions.

Hunger as a sensation

The official definition used by the FAO and other organizations is expressed in terms of individual sensation. In this sense, hunger can be understood as the uncomfortable or painful physical sensation caused by insufficient dietary energy intake (FAO et al., 2025)FAO, IFAD, UNICEF, WFP, & WHO. (2025). The State of Food Security and Nutrition in the World 2025: Addressing high food price inflation for food security and nutrition. FAO. https://doi.org/10.4060/cd6008en.

This classic definition has a medical basis, related to the physiological signals the body experiences when it needs energy and nutrients. It draws on observations of the discomfort and painful contractions that occur in the stomach and intestines during fasting. It is a highly somatic definition that goes beyond the desire to eat and helps us understand the physical suffering it causes, but only in part. Caloric intake can sometimes alleviate the sensation of hunger, yet the lack of specific macronutrients and micronutrients has other consequences distinct from pain. 

Hunger as the core of the vicious cycle of poverty

Hunger is sometimes explained by its close relationship with poverty. People living in poverty have fewer opportunities to access nutritious, sufficient, safe, and varied food. This reduces the amount of energy these individuals need to carry out everyday activities. In turn, this limitation reduces their capacity to be productive or earn enough income to escape poverty (Siddiqui et al., 2020)Siddiqui, F., Salam, R. A., Lassi, Z. S., & Das, J. K. (2020). The intertwined relationship between malnutrition and poverty. Frontiers in Public Health, 8, 453. https://doi.org/10.3389/fpubh.2020.00453.

This equivalence, however, is not entirely accurate. Not all poverty causes hunger, and hunger is not always explained by low income. Often the underlying problem is not structural poverty, but rather conflict or forced displacement, problems of access to health services, water and sanitation, or inequality due to gender or other causes. In any case, the fight against hunger and its causes can help break the vicious cycle of poverty, a complex and multicausal condition in which 1.1 billion people, or 18.3% of the world's population, currently live (OPHI & UNDP, 2025)OPHI & UNDP. (2025). Global Multidimensional Poverty Index 2025: Overlapping hardships: Poverty and climate hazards. Oxford Poverty and Human Development Initiative & United Nations Development Programme. https://ophi.org.uk/global-mpi/2025.

Hunger as food insecurity and undernourishment

From a public health and global health perspective, hunger is preferably understood as the social and material condition that causes the painful sensation. In this sense, hunger can be understood as undernourishment or food insecurity, which are the two indicators used in Sustainable Development Goal 2.1: End Hunger (FAO et al., 2025)FAO, IFAD, UNICEF, WFP, & WHO. (2025). The State of Food Security and Nutrition in the World 2025: Addressing high food price inflation for food security and nutrition. FAO. https://doi.org/10.4060/cd6008en. Furthermore, food insecurity scales make it possible to identify emergency and catastrophe situations that correspond to a famine.

Undernourishment is the habitual or chronic insufficient consumption of food energy to lead a normal, active and healthy life. It is calculated from data on food availability, distribution of consumption, energy requirements and variability among individuals and households. It is estimated that, in 2024, between 638 and 720 million people were living with undernourishment, or 8.2% of the world's population. This figure, which has barely changed since 2020, reaches 22.3% in sub-Saharan Africa.

Food insecurity encompasses not only quantity, but also quality, regularity, and uncertainty about obtaining food. Since 2016, the standard for measuring it is the Food Insecurity Experience Scale (FIES), combined with other indicators. This scale asks the person surveyed whether at any point in the last 12 months there has been a time when:

  1. They have worried about not having enough food to eat.
  2. They have not been able to eat healthy or nutritious foods.
  3. They have eaten a limited variety of foods.
  4. A meal had to be skipped.
  5. They have eaten less than they thought they should eat.
  6. Their home has run out of food.
  7. They have been hungry but didn't eat.
  8. She hasn't eaten for a whole day.

This scale makes it possible to establish the severity of food insecurity, ranging from mild (uncertainty about the ability to obtain food), moderate (lack of resources for a healthy and varied diet, and occasional lack of food), and severe (having gone several days without eating anything during the year, or having run out of food entirely). It is estimated that in 2024, 28% of the world's population was living in moderate or severe food insecurity: 2.3 billion people. This figure, in slight gradual decline globally, is rising in Africa, where it affects 58.9% of the population.

The reduction in global funding from 2024 onwards, and especially from the United States in 2025, points to an acute worsening of these figures in the coming years, for which no estimates are yet available (Osendarp et al., 2025)Osendarp, S., Ruel, M., Udomkesmalee, E., Tessema, M., & Haddad, L. (2025). The full lethal impact of massive cuts to international food aid. Nature, 640. https://doi.org/10.1038/d41586-025-00898-3.

Hunger as an injustice and a violation of human rights

Although all these definitions explain what hunger is, they do not fully integrate its moral, political, and legal dimensions. However, we must be clear: hunger is not the consequence of an unequal geographical distribution of biophysical resources, but rather a terrible injustice (D'Odorico et al., 2019)D'Odorico, P., Carr, J. A., Davis, K. F., Dell'Angelo, J., & Seekell, D. A. (2019). Food inequality, injustice, and rights. BioScience, 69(3), 180–190. https://doi.org/10.1093/biosci/biz002.

The right to food is a right enshrined in the Universal Declaration of Human Rights of 1948 and by the United Nations Committee on Economic, Social and Cultural Rights (CESCR, 1999)UN Committee on Economic, Social and Cultural Rights. (1999). General Comment No. 12: The right to adequate food (Art. 11) (E/C.12/1999/5). United Nations. https://docs.un.org/E/C.12/1999/5. This is not a mere nuance. Speaking of food as a right compels us to put on the table the obligations of States to guarantee the right not to go hungry: respecting access to adequate food, ensuring that no one deprives others of this access, taking action so that the population has the resources and livelihoods it needs, and cooperating to provide humanitarian assistance in emergency situations.

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Hunger causes malnutrition and death

What is malnutrition and what types of malnutrition are there?

Undernourishment and food insecurity are among the leading causes of malnutrition, a condition in which the intake of energy and nutrients is insufficient, excessive, or imbalanced, thereby harming health (WHO, 2024)World Health Organization. (2024, March 1). Malnutrition. Fact sheet. https://www.who.int/news-room/fact-sheets/detail/malnutrition.

The term malnutrition encompasses both undernutrition and obesity and overweight. In turn, there are several types of undernutrition: acute malnutrition, chronic malnutrition, underweight, and micronutrient deficiencies. Acute malnutrition, chronic malnutrition, and underweight are often also grouped together under the term growth faltering.

Today it is estimated that approximately 890 million adults are overweight or obese. Among children under 5 years of age, 2024 estimates indicate 150.2 million with chronic malnutrition, 42.8 million with acute malnutrition, and 35.5 million with overweight (UNICEF, WHO, & World Bank, 2025)UNICEF, WHO, & World Bank. (2025). Levels and trends in child malnutrition: UNICEF/WHO/World Bank Group joint child malnutrition estimates: Key findings of the 2025 edition. World Health Organization.

One in five deaths in children under 5 years old is related to malnutrition.

In 2019, it was estimated that nearly 50% of mortality in children under 5 years of age was attributable to malnutrition (WHO, 2024)World Health Organization. (2024, March 1). Malnutrition. Fact sheet. https://www.who.int/news-room/fact-sheets/detail/malnutrition. It is important to clarify that, in this estimate, malnutrition is understood in a broad sense, which includes low birth weight and short gestation, important consequences of maternal health and nutrition problems during pregnancy.

Considering only child growth faltering (chronic malnutrition, acute malnutrition, and underweight), the latest estimates show that in 2023, malnutrition was associated with 18.8% of all deaths in children under five years of age (approximately 880,000 deaths). This places child malnutrition as the second leading risk factor for mortality in children under five worldwide, only behind low birth weight and short gestation (Troeger et al., 2026)Troeger, C., Arndt, M., Aalruz, H., et al. (2026). Quantifying the fatal and non-fatal burden of disease associated with child growth failure, 2000–2023: A systematic analysis from the Global Burden of Disease Study 2023. The Lancet Child & Adolescent Health, 10(1), 22–38. https://doi.org/10.1016/S2352-4642(25)00303-7. Within this group, underweight is associated with the greatest mortality burden (574,000 deaths), followed by acute malnutrition (428,000 deaths) and chronic malnutrition (373,000 deaths).

Child mortality related to malnutrition is not distributed equally across countries. While the global average stands at 18.8%, it reaches 23.4% in sub-Saharan Africa, with very high proportions in South Sudan (32.8%), Niger (34.9%), and Chad (40.2%). In high-income countries, however, the fraction of child deaths attributable to malnutrition is minimal: 1.2%.

Malnutrition rarely kills immediately on its own. However, it weakens the child's immune system and increases susceptibility, severity, and mortality associated with infections (Pelletier et al., 1995)Pelletier, D. L., Frongillo, E. A., Jr., Schroeder, D. G., & Habicht, J. P. (1995). The effects of malnutrition on child mortality in developing countries. Bulletin of the World Health Organization, 73(4), 443–448. https://pubmed.ncbi.nlm.nih.gov/7554015.

Hunger and malnutrition worsen in humanitarian crises

Malnutrition has many causes and requires a multisectoral approach

Malnutrition is not caused solely by food insecurity and an inadequate diet. Among its causes are also disease, infant feeding and care practices, and lack of access to health services, water, sanitation, and hygiene (UNICEF, 2021)UNICEF. (2021). UNICEF conceptual framework on maternal and child nutrition. https://www.unicef.org/documents/conceptual-framework-nutrition. Underlying these causes are others, such as violence, poverty, gender inequality, and human rights violations. This determines that its approach must also be multisectoral (Keats et al., 2021)Keats, E., Das, J., Salam, R., et al. (2021). Effective interventions to address maternal and child malnutrition: An update of the evidence. The Lancet Child & Adolescent Health, 5(5), 367–384. https://doi.org/10.1016/S2352-4642(20)30274-1.

UNICEF Conceptual Framework on the Determinants of Maternal and Child Nutrition
UNICEF, 2021

Malnutrition can result from lack of access to health and nutrition services. After all, these services are a very important vehicle for certain actions such as micronutrient supplementation and treatment of anaemia during pregnancy, support for early initiation of breastfeeding, psychosocial and mental health support for the mother, promotion of family planning, child growth monitoring, prevention of infections through vaccination, and the diagnosis and treatment of acute malnutrition. For this reason, nutrition actions must be framed within the strengthening and resilience of health systems.

Furthermore, adequate infant feeding and childcare practices can help prevent malnutrition. Protecting these practices not only requires supporting appropriate age-adapted feeding, including breastfeeding and complementary feeding. It also means understanding the difficulties faced by caregivers, who are often overwhelmed by the circumstances in which they live, and supporting their capacity to care for young children.

Access to water, sanitation, and hygiene is also fundamental to proper nutrition (Dodos et al., 2017)Dodos, J., Mattern, B., Lapegue, J., Altmann, M., & Ait Aissa, M. (2017). Relationship between water, sanitation, hygiene, and nutrition: What do Link NCA nutrition causal analyses say? Waterlines, 36(4). https://doi.org/10.3362/1756-3488.17-00005. On one hand, people need water and obtaining it can entail an enormous cost, reducing the resources available for food, healthcare, or education. It is also essential for cooking food and maintaining hygiene to reduce the risk of infections. Deficiencies in water, sanitation, and hygiene can multiply the risk of diarrhoeal infections which, in addition to dehydration, interfere with nutrient absorption.

The vulnerability space for malnutrition expands with conflict and displacement

Malnutrition occurs at the intersection of deficiencies in food security, water security, sanitation and hygiene, coverage of health and nutrition services, social protection, and feeding and care practices. This vulnerability space is reduced by empowerment, rights, good governance, and equity. Conversely, it increases with poverty, injustice, epidemics, conflict, forced displacement, and the effects of climate change.

In humanitarian crises and emergencies, the vulnerability space of hunger is magnified (Watts & Bohle, 1993)Watts, M. J., & Bohle, H. G. (1993). The space of vulnerability: The causal structure of hunger and famine. Progress in Human Geography, 17(1), 43–67. https://doi.org/10.1177/030913259301700103. It is the result of the consequences of violence and the destruction of the social fabric at all levels:

  • At the macro level, conflicts, the effects of climate change and natural disasters can result in the forced displacement of entire populations who lose their livelihoods and are left at the mercy of government protection and humanitarian aid.
  • In the community, social cohesion and support networks can break down while violence increases, thereby heightening the vulnerability of families and caregivers (usually women) of young children.
  • Families can be affected by food insecurity, loss of life, lack of access to resources and services, distress and hopelessness, and domestic violence.
  • Ultimately, the most vulnerable individuals, among whom children figure prominently, are exposed to an extreme risk of hunger and malnutrition in all its forms.

Hunger is also sometimes used as a weapon of war

In these cases, armed groups attempt to "starve" civilians by depriving them of the resources indispensable for their survival, including access to humanitarian assistance. When this violation of international humanitarian law is intentional, it can constitute a war crime, a crime against humanity and even an act of genocide.

References

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How to cite this page

Abarca, B. (April 7, 2026). World hunger: what it is and its causes. Salud Everywhere. https://saludeverywhere.com/en/health-in-humanitarian-crises/world-hunger-and-its-causes/

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