Obesity is commonly associated with insulin resistance and hyperinsulinemia, which seem to be linked with an impaired ability to oxidize lipids, particularly in class III obese individuals [Body Mass Index (BMI): > 40 kg*m-2] (1). Exercise training is an effective strategy to improve insulin sensitivity and to reduce the risk of type 2 diabetes (2). It has been suggested that 8 (3) or 10 wk (4) of an individualized moderate exercise training program at intensity (Fatmax) that elicits maximal fat oxidation (MFO) may significantly increase the fat oxidation rates (FORs) during exercise; it may also increase the muscle oxidative capacity in overweight and class I obese men. The effects of an individualized Fatmax training program of a shorter duration have never been investigated.