What is hunger?

The sensation of hunger, a lack of food in your stomach, is universal. But there are different manifestations of hunger which are each measured in different ways:

Under-nourishment is used to describe the status of people whose food intake does not include enough calories (energy) to meet minimum physiological needs for an active life. At present, there are above 1 billion undernourished people worldwide, most of them in developing countries.

Malnutrition means 'badly nourished', but is more than a measure of what we eat or fail to eat. Malnutrition is characterised by inadequate intake of protein, energy and micronutrients and by frequent infections and diseases. Starved of the right nutrition, people will die from common infections like measles or diarrhoea.
Malnutrition is measured not by how much food is eaten but by physical measurements of the body - weight or height - and age.

Wasting is an indicator of acute malnutrition that reflects a recent and severe process that has led to substantial weight loss. This is usually the result of starvation and/or disease.