When it comes to weight loss, it's easy for personal trainers to talk the talk... But what if that trainer had to walk the walk? For 4 months, 10 personal trainers will eat what the average overweight American eats and stop working out altogether. Then each trainer surprises their overweight client and they start a weight-loss program together. At the end of a second 4-month period, they'll reveal their new weights -- will the trainer be able to lose the weight he gained? And will his weight gain help inspire his teammate?