From the different forms malnutrition takes to the global push to end all of them by 2030, click here to learn the scope of both the situation and the response.

One out of every three people in the world suffers some form of malnutrition.

Broadly speaking, malnutrition is the lack of proper nutrition. It can be the result of not having enough to eat or being unable to retain nutrients, of paradoxically eating too much or not getting enough of the right kinds of nutrients.

The forms of malnutrition are diverse. So are the consequences.

Undernutrition

Undernutrition is measured in children under five, and can take two forms: acute malnutrition and chronic malnutrition. Moderate acute malnutrition (MAM) and severe acute malnutrition (SAM) are characterized by rapid and severe weight loss, known as wasting. It happens when a child is not getting enough to eat or when an infectious disease, like diarrhea, renders a child unable to retain nutrients. In addition, MAM and SAM might be characterized by varying levels of low weight for a child’s height or abnormal fluid retention.

A median of 30 to 50 percent of cases of SAM among children under five years old are fatal, according to the World Health Organization (WHO).

Over a prolonged period of time, chronic undernutrition in infants and children can cause stunting, which is characterized by a height shorter than expected for a child’s age. Stunting has irreversible physical and cognitive effects.

For the first time in a decade, world hunger is on the rise.

The Food and Agriculture Organization (FAO) estimates 815 million people were chronically undernourished in 2016, up from 777 million in 2015. While rates of chronic child malnutrition have continued to fall, 155 million children under the age of five still suffer from stunting globally. Though undernutrition is a global problem, sub-Saharan Africa and South Asia are the worst affected, according to the 2017 Global Hunger Index.

Underscoring the threat, a region of South Sudan tipped over into famine in early 2017 – the first famine declaration in six years. Parts of three more countries – Nigeria, Somalia and Yemen – remain on the brink.

Overweight and Obesity

At the same time, overweight and obesity are also on the rise. These forms of malnutrition are linked to a combination of overconsumption – especially of foods and drinks high in sugars and fats – and too little physical activity. The WHO estimated in 2016 that 1.9 billion adults and 41 million children under the age of five were overweight or obese.

In turn, unhealthy diets and poor nutrition can spur a range of diet-related noncommunicable diseases (NCDs), including cardiovascular diseases, diabetes and some forms of cancer.

Countries are now increasingly dealing with the twin burdens of overweight, obesity and diet-related NCDs and undernutrition. It follows from the rapid transition many low- and middle-income countries are making toward less nutritious sources of food at the same time as people are living longer. The result is rapidly growing populations of people who are overweight, obese or suffering from diet-related NCDs.

Micronutrient Deficiencies

Malnutrition also includes micronutrient deficiencies in a person’s diet. Because these micronutrients are critical to development, their absence is particularly dangerous to children and pregnant women. Vitamin A deficiency, for example, is the leading cause of preventable blindness in children, according to the WHO. And that global health body has called iron deficiency “a public health condition of epidemic proportions.”

Malnutrition is truly global. The 2017 Global Nutrition Report found that 88 percent of all countries for which researchers have data face a serious burden from at least two of these forms of malnutrition – childhood stunting, anemia in women of reproductive age or overweight in adult women – if not all three.

Addressing Malnutrition

The causes of malnutrition are equally diverse and range from conflict, like in South Sudan and Yemen, to climate change to structural inequalities. Increasingly, efforts to reduce malnutrition are linked to policies and programs to simultaneously address these related issues.

The Sustainable Development Goals (SDG), adopted in 2015, present a set of 17 global goals designed to end poverty, protect the planet and ensure prosperity for all. Ending hunger by 2030 is the second of the 17 SDGs. The goal includes eliminating all forms of malnutrition. It also draws links between the effort to end hunger and eradicating poverty, generating sustainable agriculture, protecting the environment and building peace.

If progress toward more specific malnutrition targets is any indication, though, the world is not on track to reach the broader goal of ending hunger and malnutrition by 2030.

In 2012, the World Health Assembly adopted six global targets on maternal, infant and young child nutrition to be achieved by 2025. There is a broad overlap between these aims and the targets set under SDG 2, including reducing by 40 percent the number of children under five who are stunted, and dropping childhood wasting to less than 5 percent and then keeping it there.

Four of those six targets are off course, according to the 2017 Global Nutrition Report, and progress on one target is currently unclear. Only efforts to increase the rate of exclusive breastfeeding in the first six months of a child’s life to 50 percent have shown some progress. The WHO categorizes exclusive breastfeeding as a “cornerstone of child survival and child health,” because it provides irreplaceable nutrition.

Challenges

The SDGs and World Health Assembly targets have brought new attention to the dangers of malnutrition, but have not necessarily ushered in new funding. Official development assistance spending on nutrition in 2015 reached $867 million, according to the Global Nutrition Report, but that is down from a high of $870 million in 2013. Domestic spending on nutrition-specific programming did rise 29 percent between 2013 and 2015, according to an analysis of 25 countries.

Meanwhile, the Global Nutrition Report found an almost complete neglect of programs to address obesity and diet-related NCDs. Researchers found only $25.3 million in ODA disbursements to these areas in 2015 – 0.01 percent of all ODA spending in 2015.

The problems are not limited to funding, though. The FAO has highlighted the links between malnutrition and conflict, especially in areas of famine or near-famine. This is exacerbated by the effects of climate change, including drought and flood. In addition, the 2017 Global Hunger Index identified the need for greater collaboration between various stakeholders in the nutrition sector, including small-scale farmers, and for investments in data collection to improve understanding of just how widespread malnutrition is.