Drew Manning, a longtime personal trainer and admitted fitness addict, has never been overweight. He has never craved processed foods, or known what it was like to move through the world carrying dozens of extra pounds. So he decided to learn what millions of Americans, and many of his clients, live with every day.

In May 2011, Manning made the radical decision to let himself go. For six months, he stopped exercising and ate a common American diet of fast food and refined, processed snacks. Followers of his website voted on weekly food challenges, and Manning lived up to his end of the bargain by devouring towers of doughnuts or completing “the Fuddrucker Challenge” (dining on a one-pound burger, one pound of bacon cheese fries, and a huge brownie sundae, that is). The result? A seventy-pound weight gain, more than he even expected. Manning then devoted the next six months to losing the weight, sharing his meal plans, exercise strategies, ups, and downs with followers of his website.

Now, Manning is candidly describing all the details of that journey: He will reveal that at the outset, he found some joy in relaxing and allowing himself to let go of decades’ worth of health and fitness rules. He’ll detail the quickly mounting physical effects of his experiment-including plummeting energy, lower levels of testosterone, and the challenge of merely putting on his shoes-as well as the self-consciousness that came with his heavier physique. And he will consider the impact this experience had on his family, from his struggle to play with his young children to the strain his changing health and body put on his marriage. What started in his mind as physical impairment, transformed into an impactful and eye-opening emotional journey.

Obesity is epidemic in our country, but very few people can understand it from both sides. Manning’s unique, compassionate take on the issue is as fascinating to read as it is crucial to understand.