I have encountered this bug today when I had to pause in mid-workout and then independently replicated this bug it a few hours later. Apperantly, when you pause in the middle of a workout, and you successfully completed an excerise (got a green or golden checkmark) when you paused the game, then the game will still think you are doing that excerise. You can leave, then come back and unpause the game, and see you gain a lot of new carloies. Through this method, I accidentally burnt 20 new calories.
I have read previous posts about cheaters proliferating in YSFE, so I was reluctant to make this post. I only decided to do so because (1) it's not a very effective way to cheat, as you still have to "waste" valuable time, and (2) only by making this bug report can I hope that the developers fix this bug in later versions. I really don't like this bug because it means that I have to be careful when pausing the game in mid-workout, lest I come back and screw up my calorie counter.