The present invention discloses novel synergistic dietary supplement compositions comprising at least two ingredients selected from the extracts and fractions derived from Sphaeranthus indicus, Coleus aromaticus, Cissus quadrangularis, Curcuma longa, Garcinia mangostana, Citrullus lanatus, Ocimum sanctum, Trachyspermum ammi and Cinnamomum tamala as natural energy enhancer for enhancing physical performance, muscle strength, muscle mass, mental alertness and energy levels in a mammal.