Brain lactate compartmentation in neurons, astrocytes and the extracellular space is presumably of critical importance, but remains impossible to assess non-invasively. DW-MRS of lactate might capture lactate fractions in each compartment, provided these compartments induce different diffusion properties. Here we propose a framework where diffusion of cell-specific metabolites (Ins and NAA) is modeled to predict lactate diffusion in astrocytes and neurons. We use some “realistic” (spheres+cylinders) and simplified (cylinders) models of cell microstructure to show that lactate fractions in each compartment can be accurately estimated, despite inaccurate microstructure modeling. Models are finally tested on in vivo mouse brain data.