About: The Concept of the Global Hunger Index

The Global Hunger Index (GHI) is a tool designed to comprehensively measure and track hunger at global, regional, and national levels. GHI scores are calculated each year to assess progress and setbacks in combating hunger. The GHI is designed to raise awareness and understanding of the struggle against hunger, provide a way to compare levels of hunger between countries and regions, and call attention to those areas of the world where hunger levels are highest and where the need for additional efforts to eliminate hunger is greatest.

Measuring hunger is complicated. To use the GHI information most effectively, it helps to understand how the GHI scores are calculated and what they can and cannot tell us.

Assembling the GHI

How are the GHI scores calculated?

GHI scores are calculated using a three-step process that draws on available data from various sources to capture the multidimensional nature of hunger (Figure A.1).

First, for each country, values are determined for four indicators:

UNDERNOURISHMENT: the share of the population that is undernourished (that is, whose caloric intake is insufficient);
CHILD WASTING: the share of children under the age of five who are wasted (that is, who have low weight for their height, reflecting acute undernutrition);
CHILD STUNTING: the share of children under the age of five who are stunted (that is, who have low height for their age, reflecting chronic undernutrition); and
CHILD MORTALITY: the mortality rate of children under the age of five (in part, a reflection of the fatal mix of inadequate nutrition and unhealthy environments).

Second, each of the four component indicators is given a standardized score on a 100-point scale based on the highest observed level for the indicator on a global scale in recent decades.

Third, standardized scores are aggregated to calculate the GHI score for each country, with each of the three dimensions (inadequate food supply; child mortality; and child undernutrition, which is composed equally of child stunting and child wasting) given equal weight (the formula for calculating GHI scores is provided in Appendix B).

This three-step process results in GHI scores on a 100-point GHI Severity Scale, where 0 is the best score (no hunger) and 100 is the worst. In practice, neither of these extremes is reached. A value of 0 would mean that a country had no undernourished people in the population, no children younger than five who were wasted or stunted, and no children who died before their fifth birthday. A value of 100 would signify that a country’s undernourishment, child wasting, child stunting, and child mortality levels were each at approximately the highest levels observed worldwide in recent decades. The GHI Severity Scale shows the severity of hunger—from low to extremely alarming—associated with the range of possible GHI scores.

Box 1.1

WHAT IS MEANT BY “HUNGER”?

The problem of hunger is complex, and different terms are used to describe its various forms.

Hunger is usually understood to refer to the distress associated with a lack of sufficient calories. The Food and Agriculture Organization of the United Nations (FAO) defines food deprivation, or undernourishment, as the consumption of too few calories to provide the minimum amount of dietary energy that each individual requires to live a healthy and productive life, given that person’s sex, age, stature, and physical activity level.

Undernutrition goes beyond calories and signifies deficiencies in any or all of the following: energy, protein, and/ or essential vitamins and minerals. Undernutrition is the result of inadequate intake of food in terms of either quantity or quality, poor utilization of nutrients due to infections or other illnesses, or a combination of these factors. These, in turn, are caused by a range of factors, including household food insecurity; inadequate maternal health or childcare practices; or inadequate access to health services, safe water, and sanitation.

Malnutrition refers more broadly to both undernutrition (problems caused by deficiencies) and overnutrition (problems caused by unbalanced diets, such as consuming too many calories in relation to requirements with or without low intake of micronutrient-rich foods).

In this report, “hunger” refers to the index based on four component indicators. Taken together, the component indicators reflect deficiencies in calories as well as in micronutrients.

Figure A.1

Composition of the Global Hunger Index

Source: Wiesmann et al. (2015). Note: The values of each of the four component indicators are standardized. See Appendix B for the complete GHI formula and Appendix C for the data sources. SDGs = Sustainable Development Goals.

Why does the GHI incorporate four different indicators?

Using this combination of indicators to measure hunger offers several advantages. The indicators included in the GHI formula reflect caloric deficiencies as well as poor nutrition. The undernourishment indicator captures the nutrition situation of the population as a whole, while the indicators specific to children reflect the nutrition status within a particularly vulnerable subset of the population for whom a lack of dietary energy, protein, and/or micronutrients (essential vitamins and minerals) leads to a high risk of illness, poor physical and cognitive development, and death. The inclusion of both child wasting and child stunting allows the GHI to document both acute and chronic undernutrition. By combining multiple indicators, the index reduces the effects of random measurement errors.

Where do the source data for the four indicators come from?

Data for the indicators come from data collection efforts by various UN and other multilateral agencies. Undernourishment data are provided by the Food and Agriculture Organization of the United Nations (FAO). Child mortality data are sourced from the United Nations Interagency Group for Child Mortality Estimation (UN IGME). Child wasting and child stunting data are drawn from the joint database of UNICEF, the World Health Organization (WHO), and the World Bank, as well as from WHO’s continuously updated Global Database on Child Growth and Malnutrition, the most recent reports of the Demographic and Health Surveys (DHS) and Multiple Indicator Cluster Surveys (MICS), and statistical tables from UNICEF.

The GHI scores presented here reflect the latest revised data available for the four indicators. Where original source data were unavailable, estimates for the GHI component indicators were basedon the most recent available data. (Appendix C provides more detailed background information on the data sources for the 2000, 2006, 2012, and 2021 GHI scores.)

Why is a certain country’s GHI score so high (or so low)?

The key to understanding a country’s GHI score lies in that country’s indicator values, especially when compared with the indicator values for other countries in the report (see Appendix D for these values). For some countries, high scores are driven by high rates of undernourishment, reflecting a lack of calories for large swathes of the population. For others, high scores result from high levels of child wasting, reflecting acute undernutrition; child stunting, reflecting chronic undernutrition; and/or child mortality, reflecting children’s hunger and nutrition levels, as well as other extreme challenges facing the population. Broadly speaking, then, a high GHI score can be evidence of a lack of food, a poor-quality diet, inadequate child caregiving practices, an unhealthy environment, or all of these factors.

While it is beyond the scope of this report to provide a detailed explanation of the circumstances facing each country with a GHI score, our Global, Regional and National Trends and the Partner Spotlights describe the situation in select countries. Furthermore, this report offers other avenues for examining a country’s hunger and nutrition situation: country rankings based on 2021 GHI scores, along with GHI scores for selected years for each country appear in the Ranking; and regional comparisons appear in Appendix F.

GHI Severity Scale
≤ 9.9 low	10.0–19.9 moderate	20.0–34.9 serious	35.0–49.9 alarming	≥ 50.0 extremely alarming

Does the 2021 GHI reflect the situation in 2021?

The GHI uses the most up-to-date data available for each of the GHI indicators, meaning the scores are only as current as the data. For the calculation of the 2021 GHI scores, undernourishment data are from 2018–2020; child stunting and child wasting data are from 2016–2020, with the most current data from that range used for each country; and child mortality data are from 2019. In 2021, owing to the COVID-19 pandemic, the values of some of the GHI component indicators, and in turn the GHI scores, are likely to worsen, but any changes that occur in 2021 are not yet reflected in the data and scores in this year’s report.

How can I compare GHI results over time?

Each report includes GHI scores and indicator data for three reference years in addition to the focus year. In this report, the 2021 GHI scores can be directly compared with the GHI scores given for three reference years—2000, 2006, and 2012 (see Ranking). The reference years are selected to provide an assessment of progress over time while also ensuring there is no overlap in the range of years from which the data are drawn.

Can I compare the GHI scores and indicator values in this report with results from previous reports?

No—GHI scores are comparable within each year’s report, but not between different years’ reports. The current and historical data on which the GHI scores are based are continually being revised and improved by the United Nations agencies that compile them, and each year’s GHI report reflects these changes. Comparing scores between reports may create the impression that hunger has changed positively or negatively in a specific country from year to year, whereas in some cases the change may be partly or fully a reflection of a data revision.

Moreover, the methodology for calculating GHI scores has been revised in the past and may be revised again in the future. In 2015, for example, the GHI methodology was changed to include data on child stunting and wasting and to standardize the values (see Wiesmann et al. 2015). This change caused a major shift in the GHI scores, and the GHI Severity Scale was changed to reflect this shift. Since 2015, almost all countries have had much higher GHI scores compared with their scores from 2014 and earlier. This does not necessarily mean that their hunger levels rose in 2015—the higher scores merely reflect the revision of the methodology.

Can I compare the GHI rankings in this report to those in previous reports to understand how the situation in a country has changed over time relative to other countries?

No—like the GHI scores and indicator values, the rankings from one year’s report cannot be compared to those from another. In addition to the data and methodology revisions described previously, different countries are included in the ranking every year. This is due in part to data availability—the set of countries for which sufficient data are available to calculate GHI scores varies from year to year. If a country’s ranking changes from one year to the next, it may be in part because it is being compared to a different group of countries. Furthermore, the ranking system was changed in 2016 to include all of the countries in the report rather than just those with a GHI score of 5 or above. This added many countries with low scores to the ranking that had not been previously included.

Why do some countries not have a GHI score?

Because data for all four indicators in the GHI formula are not available for every country, GHI scores could not be calculated for some.

However, where possible, countries with incomplete data are provisionally categorized according to the GHI Severity Scale based on existing data and complementary reports (see Provisional Hunger Severity Designations and Existing Data for Countries with Incomplete Data). Several of these countries are experiencing unrest or violent conflict, which affects the availability of data as well as the food and nutrition situation in the country. It is quite possible that one or more of these countries would have a higher GHI score than Chad—the country with the highest 2021 GHI score—if sufficient data were available.

Likewise, GHI scores are not calculated for some high-income countries where the prevalence of hunger is very low. Even though food insecurity is a serious concern for segments of the population in certain high-income countries, nationally representative data for child stunting and child wasting are not regularly collected in most high-income countries. In addition, although data on child mortality are usually available for these countries, child mortality does not reflect undernutrition in high-income countries to the same extent it does in low- and middle-income countries.

Finally, GHI scores are not calculated for certain countries with small populations (such as Belize) or for non-independent entities or territories (such as Western Sahara).

How are provisional severity designations for countries with incomplete data determined?

For each country with up-to-date child stunting, child wasting, and child mortality values, these data were used to determine the range in which the country’s undernourishment value would need to fall for each GHI severity category. The country’s last known prevalence of undernourishment and the prevalence of undernourishment of the subregion in which it is located were used to determine the most plausible range of undernourishment values for the 2018–2020 period and therefore to determine its provisional severity designation. Each country’s last known GHI severity classification was also used as a point of reference in the evaluation. In ambiguous cases, the authors designated the country’s hunger level in the lower category.

In some cases it was not possible to even determine a provisional severity designation, such as if the country had never previously had a prevalence of undernourishment value, GHI score, or GHI designation since the first GHI report was published in 2006. Also, in one case, Libya, it was determined that the situation in country had changed to such an extent since its last inclusion in a GHI report in 2014 that it did not provide a sufficient benchmark for classification. In the case of South Sudan, and the Syrian Arab Republic, data were unavailable for three out of four GHI indicators. However, a review of the relevant information in the 2019, 2020, and 2021 editions of the Global Report on Food Crises and consultations with experts on food and nutrition insecurity in these countries made clear that designations of alarming were justified.

Footnotes

For further background on the GHI concept, see Wiesmann (2006) and Wiesmann et al. (2015).
According to Black et al. (2013), undernutrition is responsible for 45 percent of deaths among children younger than five years old.
The average minimum dietary energy requirement varies by country—from about 1,660 to more than 2,050 kilocalories (commonly, albeit incorrectly, referred to as calories) per person per day for all countries with available data in 2020 (FAO 2021).
For previous GHI calculations, see von Grebmer et al. (2020, 2019, 2018, 2017, 2016, 2015, 2014, 2013, 2012, 2011, 2010, 2009, 2008); IFPRI, WHH, and Concern Worldwide (2007); and Wiesmann, Weingärtner, and Schöninger (2006).