In a study, the Kidney Fat Indices (KFIs) of impalas and nyalas were studied to understand the influence of social class and reproduction on them. Kidney Fat Index is a technique in which the kidney is removed and weighed with the fat and once again excluding the fat. The resultant difference is the amount of fat on the kidney. The more the fat, the healthier the animal. In rut, the male nyalas had less KFIs, that did not vary much with the season. Pregnant females, both the antelopes nyala and impala, had higher KFIs than the non-pregnant ones.