Mark Muller and Richard Levins of the Institute for Agriculture and Policy Trade, point to evidence that we are net extractors of food from the Third World.
For example, many of the foods that we have encouraged (and sometimes forced) second and third world producers into growing for us are high value luxury foods, rather than traditional staple foods of that country.
Vandana Shiva, for example, has documented the large-scale replacement of traditional coastal rice farms with shrimp farms for the export market (Shiva, Stolen Harvest 23). Much of the best land in South America, Asia and Africa is now covered with coffee plantations, producing for export to wealthy nations. Suggesting that poor nations, who have now entirely adapted their agriculture and their land to grow food for rich nations should now live on their coffee and shrimp comes with some logistical problems at best. Some second and third world nations, like Brazil, which exports quite a lot of grain, or uses it for meat production for export, would be able to avoid hunger in this scenario, others would not.
Ethics of Biofuels by Sharon Astyk