Adam Slack's weight-gain journey began with an injury to his lower back.
"I had been laid up on the couch for about five to six weeks," the 37-year-old from Mays Landing, N.J., told "Good Morning America." "I didn't do anything but eat."
"That's when it really started," he said. "100 pounds turned into 200 pounds, then 400 pounds."
By 2008, the married father of four weighed 585 pounds, had high blood pressure, suffered from type 2 diabetes and struggled to complete even routine tasks.
"I used to tie his shoes. I would help him put on his pants. Everyone made fun of him because of how big his weight was," his wife, Michelle, recalled.
By June 2008, Slack's unhealthy lifestyle caught up with him and he nearly passed out during his shift as a security guard at an Atlantic City casino. His supervisor called 911 and paramedics rushed Slack to the emergency room of a nearby hospital.
It was in that emergency room at the AtlantiCare Regional Medical Center that Slack's journey to weight loss began.
"A doctor walked into my room and the first words out of his mouth were, 'Uh, hello Mr. Slack, what would you like in your obituary?'" Slack told "GMA."
"I yelled at him and told him to leave the room," he said. "It was the darkest place, but it was also a rebirth."
Dr. Irineo Bustamante was the emergency room physician who issued the blunt death warning to Slack, telling him that the hospital would cover his obituary for him.
"It just came to my mind," Bustamante, who had never before said those words to a patient, recalled. "He didn't look good. I really had to do something."
Two hours after their first meeting, Bustamante returned to Slack's room, and saw that something in his patient had changed.
"For the first time, it clicked," Slack said. "If I had one doctor, I had 100 doctors tell me 'you need to lose weight,' but it was the bluntness of what he said."
What else clicked for Slack was a new regime of exercise and a healthier diet.
Gone were the days of lying on the couch and eating one dozen eggs, a full loaf of white bread and a half-pound bag of shredded cheese for breakfast alone. In was a commitment to walking the family's German Shepherd, Thunder, each day.
"You have to get hooked on something," Slack said. "For me it was walking. It was baby steps, step by step."
Within six months, Slack was down 110 pounds. Today, he has slimmed down to a size 34 and 209 pounds, nearly half the weight from where he began.
He came full circle when he began working as a security officer at the same AtlantiCare hospital where Bustamante first issued his blunt, but motivating, words.
Though Slack could recall every pound he had dropped since his 2008 emergency room visit, he could not remember the doctor who, he says, had saved his life.
Prompted by media coverage of Slack's weight loss, hospital officials tracked down Bustamante as the physician who treated Slack, and reunited the two men at the hospital on Nov. 15.
"I was touched," Bustamante said of the cards and mementos brought by Slack's family and friends to say thanks.
The most touching for both men, however, was a baseball given to Bustamante by Slack's son, whose baseball team Slack is now able to coach.
Slack's entire family has joined him in his new, healthier lifestyle. His wife, Michelle, lost 24 pounds herself.
It all hit home one day on the baseball field with his son.
"We had just won a real big baseball game and he went to go give me a hug and he clasped behind my back," Slack said. "That was the first time I realized that my son could ever give me a hug. It was a real emotional moment for me."