This document analyzes how governments' use of trade policies to insulate domestic food prices from international volatility can exacerbate price spikes on global markets. When food prices spike up or down, governments often adjust trade restrictions to partially offset the change for domestic producers and consumers. However, the combined effect of many countries doing this is to increase international price changes. Estimates suggest trade policy changes contributed significantly, around 20-30%, to the large rice, wheat and maize price spikes of 2005-2008. Without these altered trade restrictions, international prices would not have risen as much. The document calls for multilateral disciplines on both export and import restrictions to reduce this effect in the future.