Malnutrition is usually due to an inadequate diet. However, the cause is often complex and related to poverty. Common associated factors are:

• Poverty
• Ignorance
• Parental neglect and deprivation
• Poor health services
• Frequent infections, especially diarrhoea and measles
• AIDS
• Displaced families, drought, famine and war

Poor education of women, unemployment, young mothers, poor social support in the community, war and violence, neglect and abuse, no breastfeeding, and low birth weight are all common in communities with a high prevalence of malnutrition. Failing to breastfeed in poor, rural communities will almost certainly lead to malnutrition.

In some children, malnutrition is not caused by a poor diet but is due to an illness which prevents the body from using food that is eaten. Chronic diseases and malabsorption may result in malnutrition in spite of a normal diet.