Malnutrition is a general term meaning literally “bad” nutrition. It encompasses both undernutrition and overnutrition.
Undernutrition refers to a lack of one or more nutrients – reflected in anthropometric measurements (such as height and weight), in clinical signs, or through biochemical tests. (These are discussed further in the session “Nutrition Assessment and Indicators.”)
Overnutrition, which includes both overweight and obesity, is increasingly common in the developing world. Over-consumption (of calories and/or specific nutrients) can lead to high blood pressure and stroke, diabetes, heart disease, and certain kinds of cancer.
Countries with large prevalences of both undernutrition and overnutrition are said to experience a double burden of malnutrition. Some families even experience this seeming contradiction within their households, with some members suffering from undernutrition while others are overweight or obese.
Nutrition indicators of primary interest in the developing world still focus overwhelmingly on those related to undernutrition, particularly for young children and women in their childbearing years.
(Sources: Black et al. 2013, EC-FAO Programme on Linking Information and Decision Making to Improve Food Security 2007, Shrimpton 2013, WHO 2012)