I've found the amount of calories I consume matters less than the kind of calories. I'm more stable eating whole foods, no refined sugars, and no gluten regardless of whether I'm exercising. I eat lots of brown rice, vegetables, fruit, nuts, and lean protein sources. However, I've come to understand that sufficient regular sleep cycles is the most effective thing I can do at thus point. Bar none, nothing helps me with mood and coping with stress like keeping a good sleep schedule.

So, I wouldn't be so quick to implicate exercise as a cause for anything, although over training can put just about anyone in an unstable state of being. Intensive training with lack of sleep doesn't gI've the body/mind the rest it needs to stay entirely functional. Put a nutritional deficit on top of it and I would expect things to deteriorate for anyone, regardless of whether or not they have bipolar.

It's important to learn what our bodies need to function, especially for people like us as bipolar places substantial physiological strain upon us. We, honestly, need more sleep, consistent exercise, and better nutrition than normal people.