The first Born approximation is used to calculate cross sections for electron loss from fast metastable hydrogen atoms passing through atomic hydrogen and atomic helium. Full account is taken of double transitions and in the case of a helium target the calculations are performed using length and velocity formulation values of the Born matrix elements. The results are remarkable for their prediction of double maxima in the cross sections and for the excellent agreement in shape with experiment over the energy range (10-30keV) which lies between the maxima.