OK, so multiple issues here.
Recall that whatever they experienced at the kennel was likely stressful for them, ...not just the separation but meal and exercise issues...so you do not want to add to that by making radical adjustments or doing some crash diet. I would first (calmly) try to find out what happened there, did they mix up the food? Did they just add too much? If it's the former, I would treat this like you would if you were switching foods, adding her regular food slowly to the mix of whatever she's now accustomed to to avoid stomach upset. If its the latter an adjust more of the right food, then gradually reduce it over the course of a week or so to her regular amount Likewise with exercise, if she's been cooped up avoid the temptation to floor it, but gradually get back into her regular exercise routine.