Hunger is chronic undernourishment. The hungry of the world have enough food to survive, but not enough food for good health, on a continuing basis. The FAO describes hunger in this way:
“People who are chronically hungry are undernourished. They don’t eat enough to get the energy they need to lead active lives. Their undernourishment makes it hard to study, work or otherwise perform physical activities. Undernourishment is particularly harmful for women and children. Undernourished children do not grow as quickly as healthy children. Mentally, they may develop more slowly. Constant hunger weakens the immune system and makes them more vulnerable to diseases and infections. Mothers living with constant hunger often give birth to underweight and weak babies, and are themselves facing increased risk of death. Every day, millions of people around the world eat only the bare minimum of food to keep themselves alive.” (What is Chronic Hunger?)
World hunger is endemic; it is a continuous, deeply-entrenched, and widespread problem. The number of hungry in the world has been in the range of 750 million up to 1 billion or so persons (very approximately) for many decades.
Famine is a different problem. Persons afflicted by famine do not have enough food to survive. If they do not obtain food, to relieve the famine, they will die. A famine does not continue to affect the same population for a long time. The fundamental difference between famine and hunger is found in whether the people have enough food to survive, or not.
As it happens, this distinction gives us insight into which types of food the hungry of the world need. If you do not have enough carbohydrates, you will not survive, no matter how much protein and dietary fat is in your diet. If you have sufficient carbs, you can survive with sub-optimum levels of protein and fat in your diet; you will not have good health, but you will survive. Since the hungry have enough food to survive, they have enough carbs.
So hunger is primarily a lack of sufficient dietary fat and/or protein. A small percentage of the hungry may be teetering on the edge between hunger and famine, in which case they will need some additional carbs as well. But the majority of the problem is based on a lack of fat and protein, not carbs.
This conclusion is borne out by my analysis of the FAO nation by nation data (2008 Hunger Report). In almost every case, except in a few of the most afflicted nations, the population had enough carbs, but they were lacking in dietary fat, or protein, or both.