About malnutrition

Malnutrition can take many forms and as such presents a large-scale and complex problem across the world. It affects most of the global population, irrespective of location, age, wealth or gender. It is a truly universal problem. Learn more about the current state of malnutrition around the world in the 2021 Global Nutrition Report: The state of global nutrition.

Definition of malnutrition

Many factors cause malnutrition. Suboptimal diets is one, but other factors also play a role – for example, food security, health status, education, social and gender relations, sociocultural and behavioural nuances, environmental and economic conditions, political situations, technology and infrastructure.

Malnutrition is often split into two broad groups of conditions:

undernutrition, including stunting, wasting, underweight and micronutrient deficiencies
overweight, obesity and diet-related non-communicable diseases (NCDs).

See: World Health Organization

Types of malnutrition

Undernutrition:: Lack of proper nutrition, caused by not having enough food or not eating enough food containing substances necessary for growth and health.
Stunting in children under five:: A form of growth failure which develops over a long period of time in children under five years of age when growing with limited access to food, health and care. Stunting is also known as ‘chronic undernutrition’, although this is only one of its causes. In children, it can be measured using the height-for-age nutritional index. Stunting is often associated with cognitive impairments such as delayed motor development, impaired brain function and poor school performance, as it often causes these negative impacts.
Wasting in children under five:: Children who are thin for their height because of acute food shortages or disease. Also known as ‘acute malnutrition’, wasting is characterised by a rapid deterioration in nutritional status over a short period of time in children under five years of age. Wasted children are at higher risk of dying. In children, it can be measured using the weight-for-height nutritional index or mid-upper arm circumference (MUAC). There are different levels of severity of acute malnutrition: moderate acute malnutrition (MAM) and severe acute malnutrition (SAM).
Micronutrient deficiencies:: Suboptimal nutritional status caused by a lack of intake, absorption or use of one or more vitamins or minerals. Excessive intake of some micronutrients may also result in adverse effects. The international community has focused on several micronutrients that remain issues globally including iron, zinc, vitamin A, folate, vitamin B12 and iodine, as they are the most difficult to satisfy without diverse diets. One general indicator of micronutrient deficiencies is anaemia, as this syndrome is caused by the deficiency of many of them, and its effects are exacerbated by several diseases.
Moderate and severe thinness or underweight in adults:: A body mass index (BMI) less than 18.5 indicates underweight in adult populations while a BMI less than 17.0 indicates moderate and severe thinness. It has been linked to clear-cut increases in illness in adults studied in three continents and is therefore a further reasonable value to choose as a cut-off point for moderate risk. A BMI less than 16.0 is known to be associated with a markedly increased risk for ill health, poor physical performance, lethargy and even death; this cut-off point is therefore a valid extreme limit.
Overweight and obesity in adults:: The abnormal or excessive fat accumulation that may impair health. BMI is a simple index of weight-for-height that is commonly used to classify overweight and obesity in adults. Overweight and obesity are major causes of many NCDs, including non-insulin-dependent diabetes mellitus, coronary heart disease and stroke. They also increase the risks for several types of cancer, gallbladder disease, musculoskeletal disorders and respiratory symptoms.

Why malnutrition matters

Malnutrition matters because it presents a very real threat to human progress and holds back development across the world. As the late UN Secretary-General Kofi Annan wrote, “Nutrition is one of the best drivers of development: it sparks a virtuous cycle of socioeconomic improvements, such as increasing access to education and employment… Eradicating malnutrition is crucial to delivering on the Sustainable Development Goals’ promise of ‘leaving no one behind’”.

All types of malnutrition lead to forms of ill health and are associated with higher death rates. In fact, malnutrition is responsible for more ill health than any other cause:

undernutrition explains about 45% of deaths among children under five
overweight and poor diets elevate the risk of NCDs which in turn contribute to death and disability worldwide
avoidable deaths due to poor diet have grown by 15% since 2010 and poor diets are now responsible for a quarter of all adult deaths
micronutrient deficiencies are common contributors to poor growth, intellectual impairments, perinatal complications and increased risk of morbidity and mortality.

Without good nutrition, good health is not possible, and this comes at a cost. Malnutrition costs the world billions of dollars a year in lost opportunities for economic growth and lost investments in human capital associated with preventable deaths in both children and adults. While the costs seem high, the costs of not intervening are even higher. The estimated total economic gains to society could reach US$5.7 trillion per year by 2030 and US$10.5 trillion per year by 2050.

Learn more about why ending poor diets and malnutrition in all its forms is a goal that is intrinsically linked with some of the world’s most pressing challenges in the foreword of the 2021 Global Nutrition Report.

Photo credit: Russell Watkins/DFID