The introduction of invasive species is a growing threat to ecosystems worldwide. Some invasive animals act as predators of native species that have not yet evolved defenses to them, while other invasive animals can be a novel food source for native species. In our system, the invasive species, the red imported fire ant (Solenopsis invicta), is both predator and novel prey of the native eastern fence lizard (Sceloporus undulatus). This allows us to explore the effects of both novel predator and prey on a native species. From previous research in this system, we know that fire ants have effects on the diet, immune function, behavior, and morphology of eastern fence lizards. Here we explored the possibility that consumption of and stings from fire ants might have metabolic effects. Consumption of fire ants in male, but not female, lizards was associated with a reduction in mass of crickets consumed. There was no significant different in weight gains between treatment groups for either sex, although this may be due to insufficient sample size. We are also exploring the potential for differences in respiration between experimental groups. This research suggests that invasive species may have different effects on the metabolism of native species depending on whether they are functioning as predator or prey.