While it is well established that caffeine reduces insulin sensitivity, coffee (and tea for that matter) increases insulin sensitivity and reduces susceptibility to diabetes.
It makes sense that other chemicals in coffee may be responsible for the improved glucose response. The researchers speculated that it may be chlorogenic acid and quinides.
At this point, it seems reasonable to avoid caffeine supplements.
A single bout of exercise can reverse the insulin resistance brought on by a high fat meal. Insulin signaling improved after exercise, probably as the result of glycogen depletion.
The researchers did not specify the type of fat used in the abstract, but omega-3 polyunsaturated and monounsaturated fats improved insulin sensitivity while omega-6 polyunsaturated and saturated fats degrade it.
Collegiate runners completed a series of runs at different intensities and at different hydration states. When slightly dehydrated, they experienced higher cortisol levels and a reduced testosterone to cortisol ratio, both before and after aerobic exercise.
Dehydration is a stressor and will prompt a stress response (cortisol release). The reduced testosterone to cortisol ratio increases catabolism and will hinder progress, both in performance and body composition.
There was no difference in the maximal fat oxidation rates in trained and untrained women, and maximal fat oxidation occurred at nearly the same exercise intensity, but the trained women were able to oxidize more fat at higher intensities.