Effects of 1 week on a high fat diet (HFD), low fat diet (LFD), or normal rat chow on body composition, glycemia, serum levels of insulin, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), leptin, non-esterified fatty-acids (NEFA) and triglycerides, and energy intake in male and female rats. This evidence concerns the gene INS and Insulin resistance.