While the existing literature on rising food prices in recent years has mainly focused on the causes and calculating the number of people falling below the poverty line in developing countries, less attention has been paid to rising food prices and food security in terms of calorie intake. The main objective of this study is to fill this gap using a case study of a developing country, Sri Lanka. In this study, we estimate the change in individual calorie intake associated with food inflation using the Stone–Geary utility function. The impact at national level is assessed using a calorie intake distribution curve. The results demonstrate that the percentage of undernourished population in Sri Lanka is expected to rise rapidly with food inflation on the basis that there is no income increase during the period under consideration. However, the rise in undernourished population is remarkably low when the income effect is taken into consideration.