I wouldn't call the effects of intense mental effort "negative," but they can certainly throw me off balance. Mental work does burn some calories, but not like exercise does. So eating to rebalance makes me put on weight. (Even my friend Dan Millman, coach and athlete, says he can gain ten pounds writing a book. and it's harder for me.)
I work to rebalance my energy after I write or I offer a coaching session. It is good to be alone, be aware, and do something physical. Relaxed natural breathing, a short walk - outdoors if I can - and some stretching are all good. Gardening is good - it helps to connect to the earth after I've been in my head.
After that, I ask what feels right, and I may go for food or good company.