I'm finding this a little odd, OK, entering your time when doing an exercise, say i put in a 20 min exercise, you can do a light exercise or a hard one, and the calories are the same, so you can work your butt off and not see a difference.
I have a garmin vivoactive hr, now one thing to remember when buying one of these watches, it does not measure your intensity mins, only your heart rate, so calories you may be looking at could be wrong.