In the world today, the most common reason for people to be undernourished is because they live in areas where food does not get distributed well. In other words, it is not really a problem of a lack of food. Instead, it is a problem of poor distribution of food.
In general, there is plenty of food in the world. People in the rich world are often overfed. Food is often wasted in rich countries. By contrast, there are poor countries, and poor areas in countries, where there is not enough food. Often, rich countries try to help alleviate hunger, only to have their aid diverted to enrich the elites in the countries where undernourishment exists.
This means that changes to the distribution of food may be more important than simple efforts to grow more food. It is still a good idea to try to bring better food production techniques to the poorest areas. However, it is also important to make efforts to ensure that the food that we have gets distributed more effectively.