Ashley Morgan is in hour three of her daily four-hour workout. She runs on a treadmill in her storage unit, which is locked. She is ashamed to be seen.
The 22-year-old from Abilene, Texas, is so afraid of getting fat, every bite is a battle. Morgan has been bulimic for many years, so what goes down almost automatically comes back up.
"I couldn't keep my snack down, and I had to run to the nearest trash can," she said in an interview with "Nightline" anchor Cynthia McFadden.
Twelve hundred miles north, Marco Hernandez, a police officer just outside Detroit, has what seems to be the opposite problem.
"I eat a lot. … Things just got out of control. It's kind of like wallowing at the bottom of a pit," he said.
Hernandez is 39 years old and a father of three. He is worried about taking his kids down that pit with him.
"I wonder … is [my son] eating a lot because he's growing, or is he eating a lot because he sees the things I do?" he said.
Hernandez and Morgan are about to meet in a little West Texas town called Buffalo Gap. Four others will join them. The six will check into Shades of Hope, an eating-disorder clinic, for a week of intensive treatment.
"I will make you a promise. … If you will do the things that you're taught to do here this week, there is absolutely zero failure to it," said Tennie McCarty, who founded Shades of Hope out of her kitchen 24 years ago. Then she added, "It is the hardest thing you will ever do in your life."
McCarty is tough, passionate and dedicated to her philosophy that people who eat too much or too little have the same problem. They have an addiction more powerful than addiction to drugs or alcohol. Their problem is not with their stomach – it's with their head.
For the next six days, the six strangers will eat, sleep and live together like a family. The rules are strict: no alcohol, drugs, caffeine, outside food or chewing gum.
"It's not a fat farm. And it's not a spa," said McCarty.
What it is is a lot closer to drug or alcohol rehab, a field in which McCarty is a licensed counselor.
McCarty has ardent supporters. Others think she's "absolutely nuts," she said.
All six guests are nervous, some about eating too much, others about eating too little. McCarty's rule about eating solves that: No one may leave the table until everyone eats everything on his or plate – no more, no less.
Every day at Shades begins before dawn. McCarty, 68, leads the four overeaters on a vigorous walk. Back at the house, the two undereaters sit on the couch, forbidden from exercise, which they have a tendency to overdo. Tita, a staff member, keeps them honest.
After the walk, several guests need ice packs for headaches, a result of withdrawal from caffeine.
"It's a good reminder that … there's a strong possiblity that processed sugar affects me like a drug, that caffeine affects me like a drug," said Jim, a guest.
McCarty said this cold turkey experience is "one of the hardest things in the world for an eating-disorder person. Some of 'em go through severe detox."
Food and fitness are just two parts of the equation at Shades. The most important part of the day is the group therapy McCarty calls "the work." Each session breaks down what she sees as the psychological aspects of food addiction.
McCarty has them imagine their bodies, then asks partners to trace their actual bodies onto paper. All – overeaters and undereaters – imagine themselves as being bigger than they are. McCarty knows this feeling well -- she once weighed almost 300 pounds.