In this paper, we investigate how the activation of local food markets impacts the nutritional status of both children and adults, in a context characterized by large seasonal fluctuations in the price and availability of foodgrain. Taking advantage of the random scaling-up of a program of Food Security Granaries (FSGs) in Burkina Faso, we reach three conclusions. First, especially in remote areas where local markets are thin, food market activation considerably dampens nutri-tional stress. The effect is strongest among children, and young children in particular, for whom deficient nutrition has devastating long-term consequences. Second, and surprisingly, this benefi-cial effect is obtained despite the fact that total food consumption does not increase as a result of the external intervention. Third, it is a change in the timing of food purchase, translated into a change in the timing of consumption, that drives the nutritional improvement. A simple two-period model shows that an increase in consumption needs not take place when the price surge in the lean season is dampened. More than the waste of the foodgrain stored, it is the urge to consume purchased foodgrain which gives rise to storage imperfections: foodgrain purchased in anticipation of uncertain future supply results in immediate consumption and body mass accumulation, which is less efficient than nutrition-smoothing consumption flows.