Cats increase fatty acid oxidation when isocalorically fed meat-based diets with increasing fat content.

This study tested the hypothesis that sedentary cats have the ability to adapt to high-fat carnivore diets by increasing fat oxidation. Twenty-four hour indirect calorimetry was used to determine total energy expenditure (TEE) and macronutrient oxidation in six vasectomized male (VAS) and six ovariectomized female (OVX) cats isocalorically fed lower-fat (53% fat, 45% protein) and higher-fat (71% fat, 26% protein) meat-based diets at maintenance for 8 days. Fat oxidation increased linearly with fat intake with a mean slope of 0.91 g fat oxidized/g fat intake (P < 0.001), with no change in TEE. However, VAS male cats were able to more precisely match fat oxidation with fat intake than OVX female cats (P < 0.02). Body fat content did not significantly influence fat oxidation. These results demonstrate that cats maintain body weight during short-term isocaloric feeding of a high-fat carnivore-type diet in part by increasing fat oxidation commensurate with increases in fat intake. This ability may be an important mechanism underlying the resistance of cats to obesity, despite habitual consumption of high-fat diets.