When you work out, do circuits or do short intense 30 minute workouts, your cortisol, test and other growth hormones rise. It has been shown that around 30 minutes workout, etc, your test and GH start to come down, but cortisol stays up. So that is why doing long cardio sessions just burns muscle and not fat. Cortisol is a fat storing hormone. As well, anytime cortisol goes up and your blood sugar drops from those long hours of cardio, your adrenals release adrenaline as well to help to balance your blood sugar issues. So not only do you cause adrenal stress, and store fat with long duration of cardio, but you as well create blood sugar handling issues. With people trying to drop weight, I always recommend 2:1 ratio intervals, 30 minute circuit workouts and nothing longer. This will help to reduce fat storage, keep cortisol levels down, balance … Continue Reading