text: do reptiles have body fat? mammals and birds can accumulate fat to get them through a season with little or no food.  do reptiles do this? reptiles do not use body fat to generate heat, but they _do_ store energy as fat and use it when food supply is low, or, in the case of females, to provide nutritive substances for their eggs during the breeding season. geckoes, for instance, accumulate fat on the basal portion of their tails. thus the "fat" tail of a gecko indicates a well-fed individual.