Roughly 5.5 million people, or about 50 percent of South Sudan's population, are expected to be severely food insecure and at risk of death in the coming months.
The UN declared a famine in parts of South Sudan a week ago, but the hunger affecting an estimated 100,000 people is not being caused by adverse climate conditions.
More than three years of civil war have disrupted farming, destroyed food stores and forced people to flee recurring attacks. Food shipments have been deliberately blocked and aid workers have been targeted.
What is life like under famine?
In South Sudan, thousands of people at the epicentre of a man-made famine in South Sudan emerged from the safety of the swamps this past weekend hoping to receive emergency deliveries of food. They have gone through cycles of displacement over the past three years which have driven many of them to hide in swamps, having lost their homes, crops and livestock.
With nothing else available, they spend days foraging for wild foods such as water lily roots, fruit or fish.They also spend days walking in search of food aid through areas controlled by armed groups.
They are extremely weak, hungry, and drink unsafe water from ponds and rivers.
What does it mean to die from hunger?
When lack of food has led to an 18 percent loss of weight, the body starts undergoing physiological disturbances, according to a 1997 study of hunger strikes published in the British Medical Journal.
The body metabolism gets increasingly dysfunctional, impacting the brain and other vital organs. At that point, therapeutic feeding treatment is necessary to save their lives, as the body has lost the ability to process normal foods. When people have insufficient food over several weeks, it leads to organ failure and eventually death.
What areas are experiencing famine?
South Sudan Facts:
Population: 11.7 million
Area: 619,745 sq km (239,285 sq miles)
Life expectancy: 55.7
Child mortality: 99.2 per 1,000 live births
Undernutrition for children under five: 31.1%
Ranking in UN Human Development Index: 169 (out of 188)
