A demand system is estimated separately for Myanmar, Thailand and Vietnam. Results showed that rice, the most important staple food in these countries, is a normal good. Food demand elasticity with respect to expenditure is less elastic for higher income country like Thailand while more elastic for lower income country like Myanmar. Market shocks such as a decrease in expenditure or an increase in rice prices tend to have the largest impacts on the prevalence of undernourishment in Myanmar and Vietnam. The study concludes with a recommendation for effective safety net programs.