When Sinclair met her husband, Marty Wolverton, a corrections officer, he was the first man "not asking my bra size or what position I liked."
Though Sinclair says she accepted her size, she worried about being unhealthy. While on a honeymoon at Disney World, she had to rent a cart because her joints were so painful from the weight.
Wolverton worries that her personality will change with gastric surgery. "I have heard the divorce rate for people who undergo surgery is pretty high," he says.
But Sinclair reassures her husband: "Someone without good self-esteem took anyone who came along. When they feel better they dump the loser and try to find someone better. But I have no loser."
The couple takes out a $19,000 loan to pay for the surgery, which is performed laparoscopically to reduce the stomach to the size of an egg yolk.
Patients typically lose 2 to 10 pounds a week and can lose up to 70 percent of their weight in the first year, according to the movie.
"I'll never be a size 2, but I hope after surgery I can get to a size 18," says Whitworth, who is so large by her mid-30s that she faces an immobile life in a scooter."
She had surgery two decades ago, which was a failure. Eating five pizzas in a sitting or downing a bag of peanut butter cups or a roll of cookie dough "takes away my feelings," she says.
"[Fat acceptance groups] say it's OK being fat," says Whitworth, but nobody likes being fat. Nobody likes being different."
Whitworth says she met her husband on the Internet when he was "shopping for a fat girl."
Now, she wants their 8-year-old daughter to grow up with a healthy attitude toward food but admits she tells her, "Do as I say, not as I do."
Her insurance company will not pay for the surgery because fat is not viewed as a life-threatening condition, according to Whitworth. "I did it to myself, so they don't have to cover it."
Doctors treat these women offhandedly. "The cure for everything is a diet," says Brooks. Some are ashamed to even seek medical treatment.
One, who is homebound by her weight, is found slumped over in her chair, dead among her cats.
With Sinclair and a few other "girls" now thinner and more active, the group changes.
"The commonality we had as girls is now gone," says Brooks. "Food was our glue. We don't have that anymore. We are still friends, but it's not like it was before."
All three women plan to attend the premiere of the movie in Los Angeles. But while Sinclair and Brooks can fly, Whitworth told ABCNews.com that she will have to drive 200 miles from San Antonio because of her size. "I have to purchase two plane tickets, and that would be a nightmare."
Now 490 pounds, Whitworth is still modeling for soft porn sites, saving her money and hoping someone steps in to help her or she finds a job with full insurance coverage for weight-loss surgery.
"Our story needs to be out there," she said to ABCNews.com. "Even though we look a certain way outside, you don't know what the story is. … You can't judge a book by its cover."
Director Lescaze said that is the point of the movie.
"I hope that people realize the social stigma of being fat and how difficult it is to live and how nonconducive it is to losing weight," she said. "The film breaks the stereotypes of culturally framing fat people as lazy, dirty and stupid."