Malnutrition

Malnutrition covers any lasting mismatch between what the body needs and the energy and nutrients it actually receives. The World Health Organization groups it into three forms: undernutrition, which includes wasting (too thin for height), stunting (too short for age) and underweight; deficiencies or excesses of micronutrients, the vitamins and minerals; and overweight, obesity and the diet-related noncommunicable diseases that follow. A person can be overweight and still lack key micronutrients.

Undernutrition results from too little food, from illness that raises needs or dulls appetite, or from poor absorption of nutrients, as in chronic diarrhea or celiac disease. In children it slows growth and brain development and weakens immunity, so infections strike more often and more severely, and it is linked to nearly half of deaths in children under five. Severe protein-energy malnutrition appears as marasmus, extreme wasting from a lack of calories and protein, or kwashiorkor, in which swelling from fluid build-up masks the weight loss.

Worldwide, the most important micronutrient deficiencies are of iodine, iron and vitamin A. Malnutrition is assessed with weight, height, body mass index and, in children, growth charts and arm circumference, and it is treated by correcting the diet and the underlying cause, refeeding severely starved patients gradually.