Insulin sensitivity is enhanced by a single session of endurance exercise. However, it is unknown if increasing plasma fatty acid availability after exercise impairs insulin sensitivity, as it is known to do when sedentary. On two separate occasions, seven lean, healthy women performed 90 min of exercise at ~65% VO₂peak. After exercise, subjects ingested the same meals, with the only difference between the trials being the contents of the 16 h overnight infusion. In one trial a lipid-plus-heparin emulsion (LIPID) was infused overnight after exercise in order to increase plasma fatty acid availability, and in the other trial saline (SALINE) was infused as a control. Blood was sampled hourly during the infusion. The next morning, a muscle biopsy was taken to measure intramuscular triglyceride (IMTG) and glycogen concentrations. Three h after stopping the overnight infusion, subjects underwent an intravenous glucose tolerance test to assess insulin sensitivity, using minimal model analysis (S_i). During the overnight infusions, mean [SD] plasma fatty acid availability was ~4-fold higher (0.84 [0.359] vs. 0.22 [0.09] mmol^.L^-1, p=0.003), and the next morning IMTG was ~30% greater (49.2 [6.6] vs. 38.3 [7.7] mmol^.kg dw^-1, p=0.036) in LIPID compared to SALINE. Muscle glycogen concentration was not different between trials (p=0.82). LIPID increased systemic caloric availability, resulting in a caloric surplus of ~1100 kcal above energy balance (p=0.00001), while energy balance was maintained in SALINE. Despite the differences in fat and energy availability between trials, S_i the morning after exercise was not different between LIPID and SALINE (p=0.72). In conclusion, insulin sensitivity the morning after a single exercise session was not reduced despite overnight exposure to a 4-fold increase in plasma fatty acid availability and the systemic delivery of ~1100 excess calories.