Indeed your question is a global question of which many experts and scientist trying to solve. Of course I cannot shortly answer your question, as it needs a deep comprehensive research to answer. However, I can share you some insights based on our previous experiences as follows:
1. In some parts of the world that is fertile, an agricultural revolution to increase the production could be made.
2. In some parts of the world that is infertile, yet is isolated, the isolation should be taken down. For example, if there is a geographical isolation, an efficient transport system could be made. If there is a political isolation (embargo, war, etc.), then, political stabilisation is urged to be solved.
Most of the times, the problem does not come from geographical barriers, though.
The most important thing one can suggest is to do every thing to reduce the post harvest losses at all level of post harvest operations for all the crops( cereals, legumes,oil seeds, fruits& vegetables,meat, eggs etc). This way the losses reduced will be as if this amount has been produced. The other thing is societal awareness that one should take only such amount of food that he/she can consume at the table.