MESA density profiles for a 1M_⊙ star (top panels) and 3M_⊙ star (bottom panels) along their MS lifetimes. X is the central hydrogen mass fraction. Left panels: density vs. radius. Right panels: normalized to central density and stellar radius. Dashed and dotted lines show profiles for γ = 4/3 and γ = 5/3 polytropes, respectively.