Obesity‐resistant rats demonstrate enhanced energy sensing and metabolism

Abstract

The propensity for some individuals to develop obesity has been linked to intake of a high fat diet (HFD) and physical inactivity. However, some individuals resist obesity through improved energy sensing and other compensatory measures to maintain a healthy body weight. The purpose of the current experiment was to evaluate various metabolic variables in obesity‐resistant and obesity‐prone rats consuming a HFD. S5B/Pl and Osborne‐Mendel (OM) rats were fed a HFD or a low fat diet (LFD) for 2 weeks. Rats were then placed in metabolic chambers for 5 days to evaluate the respiratory exchange ratio (RER), spontaneous physical activity (SPA), and energy expenditure (EE). Once removed from the metabolic chambers, OM and S5B rats underwent a glucose tolerance test. Blood glucose was measured every fifteen minutes for 135 minutes following a bolus of glucose. S5B/Pl and OM rats only differed in RER when eating a LFD, whereby S5B rats demonstrated a decreased RER during non‐active times, indicating increased fat oxidation. Overall, S5B rats were not more physically active than OM rats. In the glucose tolerance test, S5B rats, regardless of diet, had lower areas under curve (AUC) than OM rats. These results demonstrate that S5B rats consuming a HFD have a greater metabolic rate during active and non‐active times and more efficient glucose control than OM rats. Interestingly, S5B rats resist weight gain through, non‐locomotive means.