Quantification of child undernutrition occurs through a continuum of interactions between indexes, child growth standards, threshold and measurement tools, that interacts one with another. In Niger, simultaneously with the Ready to Use Therapeutic Food (RUTF) revolution promoted by the humanitarian medicine, these devices of the quantification of malnourished bodies were regularly renegotiated over the last ten years. This article describes how diagnostic devices’ mutation within the therapeutic revolution articulates one another, transforming bodies metric within transnational public health, redefining the outlines of undernutrition, the normal and the pathologic; illustrating dynamics of risk construction within transnational public health policies.