The article by J. C. Waterlow discusses the need for an accepted classification and definition of protein-calorie malnutrition, emphasizing the importance of this for understanding prevalence and planning preventive measures. The author outlines the challenges in classifying malnutrition, including the need for a qualitative classification for severe cases and a quantitative classification for community studies. He reviews various classification systems, such as the Gomez classification based on weight for age and the Wellcome classification based on weight and height. Waterlow suggests that for community studies, a classification should be based on weight as a percentage of expected weight at a given height and height as a percentage of expected height for age. For severe cases, he proposes the Wellcome system, which distinguishes between marasmus, kwashiorkor, and intermediate forms. The article also highlights the importance of recording additional data and clearly defining criteria for inclusion in the classification. International comparisons using these methods are seen as valuable for understanding the syndromes and their dietary causes.The article by J. C. Waterlow discusses the need for an accepted classification and definition of protein-calorie malnutrition, emphasizing the importance of this for understanding prevalence and planning preventive measures. The author outlines the challenges in classifying malnutrition, including the need for a qualitative classification for severe cases and a quantitative classification for community studies. He reviews various classification systems, such as the Gomez classification based on weight for age and the Wellcome classification based on weight and height. Waterlow suggests that for community studies, a classification should be based on weight as a percentage of expected weight at a given height and height as a percentage of expected height for age. For severe cases, he proposes the Wellcome system, which distinguishes between marasmus, kwashiorkor, and intermediate forms. The article also highlights the importance of recording additional data and clearly defining criteria for inclusion in the classification. International comparisons using these methods are seen as valuable for understanding the syndromes and their dietary causes.