In this paper, we investigate whether and how a more steady supply of foodgrain in local markets impacts the nutritional status (measured with body-mass-indexes) 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 in Burkina Faso, we reach three conclusions. First, especially in remote areas where local markets are thin, the program considerably dampens nutritional stress. The effect is strongest among children, and young children in particular, for whom deficient nutrition has devastating long-term consequences. Second we argue that it is a change in the timing of food purchases, translated into a change in the timing of consumption, that drives the nutritional improvement. A simple two-period model shows that, once we account for various forms of storage costs, an increase in nutrition does not necessarily require larger quantity of food purchases or even consumption. Our last and unexpected conclusion is that the losses associated with foodgrain storage do not stem from physical losses in household granaries but rather from inefficient seasonal bodymass fluctuations. One plausible mechanism behind this particular storage imperfection rests on the households’ urge to consume readily available foodgrain.