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World hunger: what it is, causes and why it persists

Page updated onJuly 5, 2026

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.

Table of contents:

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 organisations 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).

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

Sometimes, hunger is explained by its close relationship with poverty. People living in poverty have fewer opportunities to access nutritious, sufficient, safe and varied food (Siddiqui et al., 2020).

This equation, 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 conflict or forced displacement, problems of access to health services, water and sanitation, or inequality due to gender or other causes.

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 as food insecurity, which are the two indicators used in Sustainable Development Goal 2.1: End hunger (FAO et al., 2025). Furthermore, food insecurity scales make it possible to identify emergency and catastrophic 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:

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

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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 a likely sharp deterioration in these figures in the coming years, for which no estimates are yet available (Osendarp et al., 2025).

Hunger as an injustice and a violation of human rights

Although all these definitions explain what hunger is, they do not fully capture its moral, political and legal dimensions. However, we must be clear: hunger is not the consequence of an unequal geographical distribution of biophysical resources — it is a terrible injustice (D'Odorico et al., 2019).

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). This is not a mere nuance. Speaking of food as a right forces 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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Causes of world hunger

The causes of world hunger, depending on how we understand this concept, lie at the intersection of deficiencies in food security, water security, sanitation and hygiene, health and nutrition service coverage, social protection, and feeding and care practices (UNICEF, 2021). This, however, is only the surface.

Beneath these direct causes of hunger lies a space of vulnerability (Watts & Bohle, 1993) shaped by economic policies, the lack of entitlements, marginalisation and, of course, poverty (Siddiqui et al., 2020).

Moreover, this space of vulnerability in which hunger arises is not static. On one hand, vulnerability is reduced by empowerment, rights, good governance and equity. On the other hand, it deteriorates suddenly and profoundly when shocks occur, caused by epidemics, economic crises, extreme climate events, forced displacement and conflict (FAO et al., 2025).

Conflict and forced displacement drive acute food crises and world hunger

In humanitarian crises and emergencies linked to violence and conflict, hunger is magnified (Watts & Bohle, 1993). 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 used as a weapon of war. In these cases, armed groups attempt to "starve" civilians by depriving them of 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.

Consequences of world hunger: malnutrition and death

Hunger causes malnutrition: what it is and what types there are

Undernourishment and food insecurity are among the main causes of malnutrition, a condition in which energy and nutrient intake is insufficient, excessive or imbalanced, thereby harming health (WHO, 2024).

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. In children under 5 years old, 2024 estimates indicate 150.2 million with chronic malnutrition, 42.8 million with acute malnutrition, and 35.5 million with overweight (UNICEF et al., 2025).

Malnutrition has many causes and requires a multisectoral approach

Malnutrition is not caused solely by food insecurity and an inadequate diet. Its causes also include disease, infant feeding and care practices, and lack of access to health services, water, sanitation and hygiene (UNICEF, 2021). Underlying these causes are others, such as violence, poverty, gender inequality and human rights violations. This means that addressing malnutrition must also be multisectoral (Keats et al., 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 for adequate nutrition (Dodos et al., 2017). 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 that reduces the risk of infection. Deficiencies in water, sanitation and hygiene can multiply the risk of diarrhoeal infections which, in addition to causing dehydration, interfere with nutrient absorption.

Hunger and malnutrition are causes of death: undernutrition is associated with one in five deaths in children under 5

In 2019, it was estimated that almost 50% of mortality in children under 5 was attributable to malnutrition (WHO, 2024). It is important to clarify that in this estimate, malnutrition is understood in a broad sense, which includes low birthweight and short gestation, important consequences of maternal health and nutrition problems during pregnancy.

If we consider only childhood 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 (approximately 880,000 deaths). This places childhood malnutrition as the second leading risk factor for mortality in children under five worldwide, second only to low birthweight and short gestation (Troeger et al., 2026). 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).

The vicious cycle of hunger, malnutrition and poverty

When studying the complex relationship between the causes and consequences of hunger, it is impossible to ignore that what actually emerges is a cruel vicious cycle, operating at multiple levels:

At the biological level, hunger causes malnutrition, and malnutrition leads to disease when nutrient deficiency weakens the immune system. In turn, disease causes malnutrition, when the body's metabolic requirements increase or nutrient absorption is impaired (Troeger et al., 2026).
At the socioeconomic level, poverty and a lack of income limit access to services and to sufficient, good-quality food. At the same time, this reduces people's capacity to carry out everyday activities, to be productive, and to earn enough income to lift themselves out of poverty (Siddiqui et al., 2020).
At the intergenerational level, hunger and malnutrition perpetuate themselves and are passed from parents to their children, sometimes through irreversible cognitive and physical damage (Siddiqui et al., 2020).

For all these reasons, the fight against world 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, live (OPHI & UNDP, 2025).