Band inversion gives rise to unique physical phenomena in topological insulators, such as the quantum spin Hall effect and the emergence of gapless surface states. In the bulk, band inversion can lead to highly warped, nonparabolic bands near the k-point at which the inversion occurs, where the concept of valley degeneracy (i.e. number of carrier pockets available for charge carrier transport) becomes important. In tetradymite Bi2Te3 for example, multiple valence and conduction band pockets form around the Γ-point due to strong band inversion. The valley degeneracy can have a crucial impact on the electrical transport properties of a material. In thermoelectric materials especially, increasing the valley degeneracy has the advantage of enhancing the thermopower without compromising the carrier mobility in the absence of intervalley scattering. Recent studies have therefore begun to explore the possibility of enhancing the thermoelectric performance of materials via band inversion. As a result, there is a need to understand how band inversion warps the bulk electronic structure and affects the ensuing valley degeneracy.