The paper begins with an overview of the changing nature of global food system and an exposition of the concept of food insecurity. It's time to rethinking how to build up and keep a sizeable buffer stock of food grains to meet the situations that may arise as a result of shortfalls. This paper provides a conceptual framework for understanding the market process under the intervention of buffer stock scheme. In the scheme, physical grain reserves is established for the purpose of countering extreme fluctuations in food prices and discouraging excess speculation, as well as meeting emergency needs. A special feature of the model is that the interplay between food production shocks and market speculation plays a decisive role in determining the adequacy of foodgrain buffer stock.