Food security and hunger

People have food security when they consistently have physical and economic access to sufficient, safe and nutritious food for a healthy, active life. A country can have food available without every household being able to afford or access it.

The food security index combines several indicators of a country's food-security conditions into a composite measure. Its central dimensions include food affordability, availability, and quality and safety. A higher score generally indicates stronger food security. The index measures conditions that support access to food; it does not directly measure every person's nutritional health.

Commonly measured by the Global Hunger Index, the hunger index combines undernourishment, child wasting, child stunting and mortality among children under five. Higher scores indicate more severe hunger. Child mortality reflects how inadequate nutrition interacts with disease and other poor living conditions, so it isn't exclusively a measure of food intake.

The two indices answer different questions. Even with substantial food supplies, a country may experience hunger because low-income households cannot obtain an adequate diet. Composite scores also depend on which indicators and weightings are used. These may change between editions.

Calories and malnutrition

Calories per capita measure the average daily food energy available or consumed per person, usually expressed in kilocalories per person per day. Check what the dataset measures: national food supply or actual intake. Some of the food counted as available is wasted.

A national average doesn't show how food is distributed. Nor does energy intake alone reveal diet quality: a calorie-rich diet can still lack essential vitamins and minerals.

An imbalance in energy or nutrient intake, including deficiencies and excesses, is called malnutrition. Its indicators include:

• Undernourishment: habitual food-energy intake below the level needed for a healthy, active life.
• Stunting: low height for age in children, indicating the accumulated effects of poor nutrition and illness.
• Wasting: low weight for height in children, often associated with recent weight loss or acute undernutrition.
• Underweight: low weight for age, which can reflect stunting, wasting or both.
• Micronutrient deficiencies: inadequate intake or absorption of essential vitamins and minerals.
• Overweight and obesity: excessive body fat that increases health risks, commonly assessed using body mass index in adults.

Global patterns and hidden disparities

Higher-income regions, such as much of Europe and North America, generally have stronger food security. Severe hunger and child undernutrition are more concentrated in parts of sub-Saharan Africa and South Asia, though conditions vary greatly within both regions. Conflict, poverty and disrupted supply systems can create exceptions to these broad income-based patterns.

Overweight and obesity occur worldwide, including outside affluent countries. Within a country, community or household, undernutrition can coexist with excess weight. This is the double burden of malnutrition. National indicators can conceal differences between income groups, between rural and urban areas, and between women and men. Using several indicators together gives a more reliable picture than treating one national average as the whole story.

The nutrition transition

The nutrition transition describes changes in diets and nutritional outcomes associated with economic, social and demographic change. Diets commonly shift away from staple grains and other minimally processed foods towards greater consumption of animal products, refined carbohydrates, fats, sugars and highly processed foods.

As incomes rise, households can buy a wider range of foods. Urbanization changes access to shops and food services. Changes in work patterns can also increase demand for convenient meals, while food processing, advertising and international trade make packaged foods more widely available. Lifestyles often become less physically active alongside these changes.

A more varied diet can reduce some nutrient deficiencies. Yet eating more energy-dense, nutrient-poor foods can increase overweight and obesity. The transition isn't a simple progression from poor nutrition to good nutrition.

Regional variation in consumption and choice

There is no fixed sequence that every region follows at the same speed. Higher-income regions often consume large amounts of processed foods and animal products. In many rapidly urbanizing middle-income regions, obesity is increasing while child undernutrition continues. Poorer rural communities may still depend heavily on staple foods, even when affluent groups in the same country eat much more varied diets.

Income shapes what people can afford. Food choices also reflect culture, religion, local production, prices and access. Pulses, for example, can remain important where vegetarian traditions are strong. Rice or maize may keep their central place in the diet even as people eat more packaged snacks.

In cities, inexpensive processed foods may be easier to find than fresh, varied foods. A high-calorie diet doesn't necessarily indicate affluence or informed nutritional choice. Awareness of health risks encourages some higher-income groups to choose more vegetables and whole grains, with less highly processed food. Cost and access, however, affect who can make that shift.

What the indicators measure

Health indicators tell us about different aspects of health. Some measure length and quality of life; others track survival at vulnerable ages or access to services. Read them together. No single indicator captures all these dimensions.

Health-adjusted life expectancy (HALE) is the average number of years a person can expect to live in full health, allowing for time lived with illness or disability. Measured in years, it is lower than ordinary life expectancy because not every year lived is healthy.

Deaths before the first birthday, counted per 1,000 live births in a given period, are measured by Infant mortality. This indicator reflects conditions affecting infants, including maternal health and nutrition, as well as sanitation and access to care.

Maternal mortality is commonly reported as the maternal mortality ratio. It counts deaths from causes related to or aggravated by pregnancy or its management, during pregnancy or within 42 days of its end, per 100,000 live births. Accidental and incidental deaths are excluded.

Access to sanitation measures the proportion of people able to use facilities that hygienically separate human excreta from human contact. When comparing places, use the same service category. Access to a basic toilet service is not the same as access to safely managed waste treatment.

The doctor-to-population ratio compares the number of doctors or physicians with the population they serve. Figures may be reported as doctors per 1,000 people or as people per doctor. More doctors per 1,000 generally suggests better provision; more people per doctor suggests worse provision.

Global patterns

Wealthier regions generally have higher HALE, sanitation coverage and physician availability. Infant and maternal mortality tend to be lower where people have better access to nutrition and preventive care, along with skilled maternity services and treatment. Much of sub-Saharan Africa has comparatively high infant and maternal mortality and low physician availability. Many European countries show the opposite profile.

These are broad tendencies, not universal rules. Public provision can support relatively good health outcomes even at modest income levels. By contrast, conflict or severe inequality can worsen outcomes in otherwise well-resourced places. Health indicators often improve over time, but disruption to services can halt or reverse that progress.

Comparing places carefully

National averages hide uneven access. Doctors often concentrate in large cities, leaving remote rural communities underserved. Even a favourable national doctor ratio does not establish that care is affordable, geographically accessible or equally distributed.

Low infant mortality doesn't mean adults experience little illness. Nor does long life expectancy mean that all those years are healthy. Comparing HALE with ordinary life expectancy helps distinguish longevity from healthy longevity. Comparisons between places can also be affected by differences in how births and deaths are registered, by survey coverage and by indicator definitions.

The epidemiological transition

The epidemiological transition describes a long-term shift in the main causes of illness and death, commonly from infectious diseases towards chronic, non-communicable diseases. It concerns a population’s changing disease profile. The nutrition transition, by contrast, concerns changes in diets and nutritional outcomes.

Infectious diseases cause much illness and premature death where poor sanitation, inadequate nutrition and limited treatment are widespread. Better sanitation and nutrition, together with vaccination and healthcare, reduce many of these deaths. More people then survive into later life, so chronic conditions such as cardiovascular disease, cancer and diabetes account for a larger share of illness and mortality.

One disease group does not completely replace the other. Infectious diseases persist in wealthy societies; non-communicable diseases are also widespread in lower-income societies. Outbreaks or disruption to healthcare can interrupt the transition.

The diseases continuum

The diseases continuum describes an overlapping range, from diseases associated with poverty to those associated with affluence. This is more useful than dividing countries into two separate disease categories.

Diseases of poverty are associated with deprivation: unsafe water and poor sanitation, inadequate nutrition, or limited access to prevention or treatment. Diarrhoeal disease shows how an infection can become especially dangerous when these conditions combine.

Patterns such as high-energy diets, low physical activity and longer survival are associated with Diseases of affluence. These patterns can increase the importance of conditions such as type 2 diabetes and cardiovascular disease. The label doesn’t mean that only wealthy people are affected. Poorer groups may face substantial exposure and have less access to treatment.

Many countries face a double burden of disease: infectious diseases remain important while non-communicable diseases increase. Their health services must address acute infections as well as long-term prevention and treatment.

Ageing and disease burden

Disease burden is the combined impact of illness, disability and premature death on a population. With population ageing, fewer people may die early, yet more may live for years with chronic illness or disability.

As older people make up a larger proportion of the population, dementia and cardiovascular disease become more prominent, along with multiple simultaneous chronic illnesses. Demand grows for continuing treatment and rehabilitation, support with daily activities and long-term care—not just short episodes of medical treatment.

Ageing changes both the scale and the type of healthcare demand. Regions with advanced population ageing already face these pressures. Those ageing rapidly at lower income levels may face them while infectious disease burdens remain substantial. More chronic illness in an older population does not necessarily mean that health is worsening at every age: it can partly reflect success in keeping people alive longer.