This paper revisits the issue of estimating the relationship between calorie intake and income, and presents and compare estimates of this relationship for China and Vietnam. Semiparametric generalized additive models are estimated and their performances are compared to the performance of the classical double log model using the revealed performance test of Racine and Parmeter (2014). This methodology is implemented using successive waves of the Chinese Health and Nutrition Survey and of the Vietnam Household Living Standard Survey. The application delivers some new and interesting insights on nutritional transition in the two countries between 2004 and today.