The intestinal microbiota is known to influence postnatal growth. We previously found that a strain of Lactiplantibacillus plantarum (strain Lp ^WJL ) buffers the adverse effects of chronic undernutrition on the growth of juvenile germ-free mice. Here, we report that Lp ^WJL sustains the postnatal growth of malnourished conventional animals and supports both insulin-like growth factor–1 (IGF-1) and insulin production and activity. We have identified cell walls isolated from Lp ^WJL , as well as muramyl dipeptide and mifamurtide, as sufficient cues to stimulate animal growth despite undernutrition. Further, we found that NOD2 is necessary in intestinal epithelial cells for Lp ^WJL -mediated IGF-1 production and for postnatal growth promotion in malnourished conventional animals. These findings indicate that, coupled with renutrition, bacteria cell walls or purified NOD2 ligands have the potential to alleviate stunting.