This paper presents an evolutionary population synthesis (EPS) model that calculates spectral energy distributions, colors, stellar mass-to-light ratios, bolometric corrections, and near-infrared spectral line indices for a wide range of metallicities, ages, star formation histories, initial mass functions, and Horizontal Branch morphologies, including blue morphologies at high metallicity. The model evaluates the energetics of post-main sequence evolutionary phases using the fuel consumption theorem and assesses the impact of different stellar evolutionary tracks on the models. The models are calibrated with globular cluster data from the Milky Way and the Magellanic Clouds, as well as the merger remnant galaxy NGC 7252, for ages ranging from old to young (0.1 to 2 Gyr). The contribution of the Thermally-Pulsing Asymptotic Giant Branch (TP-AGB) phase is emphasized, as it is crucial for modeling young stellar populations. The combination of near-IR spectral indices C2 and H2O is shown to be useful for determining the metallicity of 1 Gyr stellar populations. As an application, the spectral energy distributions of high-redshift galaxies (2.4 ≤ z ≤ 2.9) observed with the Spitzer Space Telescope are re-analyzed, and the models, including TP-AGB stars, are found to reproduce the high rest-frame near-IR fluxes well, suggesting formation redshifts around z ∼ 3 − 6.This paper presents an evolutionary population synthesis (EPS) model that calculates spectral energy distributions, colors, stellar mass-to-light ratios, bolometric corrections, and near-infrared spectral line indices for a wide range of metallicities, ages, star formation histories, initial mass functions, and Horizontal Branch morphologies, including blue morphologies at high metallicity. The model evaluates the energetics of post-main sequence evolutionary phases using the fuel consumption theorem and assesses the impact of different stellar evolutionary tracks on the models. The models are calibrated with globular cluster data from the Milky Way and the Magellanic Clouds, as well as the merger remnant galaxy NGC 7252, for ages ranging from old to young (0.1 to 2 Gyr). The contribution of the Thermally-Pulsing Asymptotic Giant Branch (TP-AGB) phase is emphasized, as it is crucial for modeling young stellar populations. The combination of near-IR spectral indices C2 and H2O is shown to be useful for determining the metallicity of 1 Gyr stellar populations. As an application, the spectral energy distributions of high-redshift galaxies (2.4 ≤ z ≤ 2.9) observed with the Spitzer Space Telescope are re-analyzed, and the models, including TP-AGB stars, are found to reproduce the high rest-frame near-IR fluxes well, suggesting formation redshifts around z ∼ 3 − 6.