A malnourished child is not the same as a starving one. They may not even be hungry, if they get enough calories. But what kind of calories? A child needs protein to grow and micronutrients are essential to development. Millions lack both.

The consequences can be seen in the distended bellies, peeling skin and thinning hair typical of the malnourished child. They may be irritable, apathetic or anxious. Their brains grow more slowly, with changes similar to those in children with mental retardation from other causes.

The younger they suffer malnourishment, the worse the outcome. Their physical growth is slowed, cognitive development arrested and their immune systems fail to mature, putting them at heightened risk from infection.

Malnutrition contributes to more than half of child deaths worldwide. It affects virtually every organ system, causing fatty degeneration of the liver and heart and atrophy of the bowel. Its impact on the immune system is similar to that of Aids. The common result is diarrhoea, which in turn worsens the malnutrition.

The commonest deficiencies include iron, lack of which causes fatigue and anaemia, iodine (developmental delay), Vitamin D (poor growth and rickets), vitamin A (night blindness) and zinc (poor wound healing).

Globally, malnutrition is the most important cause of illness and death. The commonest cause in the developing world is lack of food, but it may also result from infection or illness, which prevents the child eating or absorbing nutrients from food.

A malnourished adult can survive until the next harvest. But a malnourished child will have its development stunted, with consequences that will be felt for life.