Stunting, wasting, overweight and underweight

What do these indicators tell us?

The indicators stunting, wasting, overweight and underweight are used to measure nutritional imbalance; such imbalance results in either undernutrition (assessed from stunting, wasting and underweight) or overweight. Child growth is internationally recognized as an important indicator of nutritional status and health in populations.

The percentage of children with a low height-for-age (stunting) reflects the cumulative effects of undernutrition and infections since birth, and even before birth. This measure can therefore be interpreted as an indication of poor environmental conditions or long-term restriction of a child’s growth potential. The percentage of children who have low weight-for-age (underweight) can reflect wasting (i.e. low weight-for-height), indicating acute weight loss or stunting, or both. Thus, underweight is a composite indicator that may be difficult to interpret.

Stunting, wasting and overweight in children aged under 5 years are included as primary outcome indicators in the core set of indicators for the Global nutrition monitoring framework to monitor progress towards reaching Global Nutrition Targets 1, 4 and 6. These three indicators are also included in WHO’s Global reference list of 100 core health indicators.

How are these indicators defined?

These indicators are defined as follows:

·   stunting – height-for-age ≤-2 SD of the WHO Child growth standards median;

·   wasting – weight-for-height ≤-2 SD of the WHO Child growth standards median; and

·   overweight – weight-for-height ≥+2 SD of the WHO Child growth standards median.

·   underweight – weight-for-age ≤-2 standard deviations (SD) of the WHO Child growth standards median;

What are the consequences and implications?

Stunting – Children who suffer from growth retardation as a result of poor diets or recurrent infections tend to be at greater risk for illness and death. Stunting is the result of long-term nutritional deprivation, and often results in delayed mental development, poor school performance and reduced intellectual capacity. In turn, this affects economic productivity at the national level. Women of short stature are at greater risk for obstetric complications because of a smaller pelvis. Also, small women are at greater risk of delivering an infant with low birth weight, contributing to the intergenerational cycle of malnutrition, because infants of low birth weight or retarded intrauterine growth tend be smaller as adults.

Wasting – Wasting in children is a symptom of acute undernutrition, usually as a consequence of insufficient food intake or a high incidence of infectious diseases, especially diarrhoea. In turn, wasting impairs the functioning of the immune system and can lead to increased severity and duration of, and susceptibility to, infectious diseases, and an increased risk of death.

Overweight – Childhood obesity is associated with a higher probability of obesity in adulthood, which can lead to a variety of disabilities and diseases, such as diabetes and cardiovascular diseases. The risks for most noncommunicable diseases (NCDs) resulting from obesity depend partly on the age at onset and the duration of obesity. Obese children and adolescents are likely to suffer from both short-term and long-term health consequences, the most significant being: cardiovascular diseases, mainly heart disease and stroke; diabetes; musculoskeletal disorders, especially osteoarthritis; and, cancers of the endometrium, breast and colon.

Underweight – Weight is easy to measure; hence, this is the indicator for which most data have been collected in the past. The mortality risk is increased in children who are even mildly underweight, and the risk is even greater in severely underweight children.

Cut-off values for public health significance

Source: de Onis et al. (2018).

Source of data

WHO. Global database on child growth and malnutrition (http://www.who.int/nutgrowthdb/en/).

Further reading

de Onis M, Borghi E, Arimond M, Webb P, Croft T, Saha K et al. Prevalence thresholds for wasting, overweight and stunting in children under 5 years. Public Health Nutrition. 2018;1–5. doi:10.1017/S1368980018002434.

WHO. Global nutrition targets 2025: stunting policy brief. Geneva: World Health Organization; 2014 (http://who.int/nutrition/publications/globaltargets2025_policybrief_stunting/en/).

WHO, United Nations Children’s Fund (UNICEF), World Food Programme (WFP). Global nutrition targets 2025: wasting policy brief. Geneva: World Health Organization; 2014 (http://who.int/nutrition/publications/globaltargets2025_policybrief_wasting/en/).

WHO. Global nutrition targets 2025: childhood overweight policy brief. Geneva: World Health Organization; 2014 (http://www.who.int/nutrition/publications/globaltargets2025_policybrief_overweight/en/).

WHO, UNICEF. Global nutrition monitoring framework: operational guidance for tracking progress in meeting targets for 2025. Geneva: World Health Organization; 2017 (http://www.who.int/nutrition/publications/operational-guidance-GNMF-indicators/en/).

WHO. Global reference list of 100 core health indicators (plus health-related SDGs). Geneva: World Health Organization; 2018 (https://www.who.int/healthinfo/indicators/2018/en/).

Internet resources

WHO. Child growth standards. Publications and peer-reviewed articles. (http://www.who.int/childgrowth/publications/en/).

WHO, UNICEF. Recommendations for data collection, analysis and reporting on anthropometric indicators in children under 5 years old. Geneva: World Health Organization; 2019 (https://www.who.int/nutrition/publications/anthropometry-data-quality-report/en/).

UNICEF–WHO–The World Bank: Joint child malnutrition estimates – levels and trends. (http://www.who.int/nutgrowthdb/estimates/en/).

WHO. Global targets 2025 to improve maternal, infant and young child nutrition. (http://who.int/nutrition/global-target-2025/en/).

WHO. e-Library of Evidence for Nutrition Actions (eLENA). Interventions by global target. (http://www.who.int/elena/global-targets/en).

Target 1: 40% reduction in the number of children under-5 who are stunted (http://www.who.int/elena/global-targets/en/#stunting).

Target 4: No increase in childhood overweight (http://www.who.int/elena/global-targets/en/#childhoodoverweight).

Target 6: Reduce and maintain childhood wasting to less than 5% (http://www.who.int/elena/global-targets/en/#wasting).