Regarding the calorie expenditure of conventional cardio as compared to HIIT (such as the Tabata protocol or the like), my understanding is that, although more calories may be expended during the longer regular cardio workout, the prolonged elevation of the metabolism using the HIIT approach will more than offset. Plus HIIT may add a bit of lean muscle tissue, whereas regular cardio, not so much. (As you may have noticed, I'm still selling the idea to myself.)
It's actually not as much as you would think. EPOC, in general you're looking at burning about an additional 100 kcals post exercise. Not all that much. Everyone is different of course. Realistically though exercise is an inefficient way of reducing calories. Just don't eat the donut lol. Much easier saving 500 kcals from food versus trying to burn 500 kcals through exercise.
