Doug Armstrong was a morbidly obese man who sought help with weight loss on TLC's "My 600-lb Life." The father of three managed to lose an eye-popping 220 pounds after bariatric surgery on the reality television show. But the shocking trauma behind Armstrong's obesity is the real eye-opener. Armstrong talked about it in a heart-breaking reveal last episode, and processing and healing that PTSD-like pain meant the difference between weight loss success and failure.

Doug Armstrong's obesity rooted in child sexual abuse

Like so many others on "My 600-lb Life" Doug's story revealed sexual molestation in childhood.

But the commonality of child sexual abuse makes the story no less gut-wrenching. You could feel the suffering as the 6' 6" man re-lived with the reality television show therapist, his terrible experience. Images of Armstrong throughout the years show a happy, loving boy with a dazzling smile. In each successive image the smile still beams, but viewers now know it hides a mountain of hurt. For some unaccountable reason, child sexual abuse victims internalize molestation. They feel responsible, guilty, and ashamed -- and at the end of that is often obesity.

Doug Armstrong treats pain with comfort eating

Child sexual abuse victims rarely tell anyone if there's even anyone to tell. They don't want to worry grown-ups or hurt their parents.

Doug couldn't tell his mom because she had abandoned him and his brother. Dad was gone a lot in the military. Kids like Doug bear that big, fat secret alone, crying in their pillows. They experience depression and PTSD. They carry the shame of the perpetrator's ugly behavior, telling only their stuffed animals. But Doug Armstrong found another friend in comfort food.

His aunt tells the "My 600-lb Life" audience how the boy, always overweight, started binging. He'd gorge on dessert and throw up in his bed. This "eating disorder" took him from overweight to obese.

Doug Armstrong pays the pain forward

What you can get away with in childhood doesn't work too well in adulthood. All that overeating left Doug at 684 pounds at just 36-years- old.

And he was a husband and father now. With the prospect of bedridden morbid obesity facing him, the young dad decided to turn things around. Dr. Younan Nowzaradan performed gastric bypass surgery but the TLC Reality TV celebrity only shed 19 pounds in two months. Dr. Now sent him to a therapists on "My 600-lb Life" to find out what was de-railing weight loss. That's when the child sexual abuse came out, and that was also when Armstrong began to heal -- and with that dazzling smile, he's lighting up his world.