Practically anyone can lose weight. But those who keep it off are a rare species. Theirs is not an entirely mysterious phenomenon—they stay slim by maintaining the behaviors that got them there. They eat healthier foods, decrease portion sizes and exercise.

But how, exactly, do they keep it up? The answer suggests a psychological overhaul as much as a physical one.

Diane Berry, a nurse practitioner and postdoctoral fellow at the Yale School of Nursing, conducted in-depth interviews with true weight-loss champions: 18 women who had lost at least 15 pounds and up to 144 pounds, and all had kept it off for an average of seven years. “Eighty-five to ninety percent of people regain any weight they’ve lost within 3-5 years, so these were the real outliers.” Except for one, the women were involved in either a Weight Watchers or TOPS program.

Common patterns jumped out from the women’s success stories. Each tale began with a fragile character: Before losing weight, she was self-conscious, vulnerable and unaware of events that contributed to the weight gain.

She crossed over into another pattern when she recognized her problem—often after receiving a nasty comment or having to buy a dress in the next larger size—and decided to change. And once she pledged to tackle her weight, her mood shifted. She suddenly had more energy, a fresh outlook.

In the next pattern, the women actively engaged in behavior changes. And in the throes of the final phases, they incorporated these new behaviors until they became second nature. They leaned on a support system (most often family members or fellow weight-loss program participants) to reinforce their behavioral changes, and they consistently monitored themselves, by stepping on a scale at least once a week, for example.

They at last dispensed with popular notions of a quick fix. “The women recognized that this is something they will have to work at for the rest of their lives”

One 82-year-old woman who lost over a hundred pounds when she was in her 60s told Berry: “I’m like an alcoholic. I am addicted to food. I wake up every morning and have to be mindful of what I eat everyday.”

Most telling was that the women did not flow automatically from one stage to the next. Each one slipped backwards at one time or another, caught her footing and then hoisted herself back up.

These women had not only altered their appearance and improved their health—they became different people. They experienced increased confidence and self-esteem and, finally, felt a sense of control over their lives.

Some reported they were more comfortable speaking out and being heard. Others were no longer emotionally responsive to others in a self-deprecating way. Many felt happier than they had been in years.

Berry also interviewed two women who were not able to keep off weight they lost, for comparison’s sake. “They were aware of portion control and the importance of exercise but couldn’t sustain the changes,” she reports. “I truly believe their life was in crisis. Everybody lives with a certain amount of crisis. But they didn’t have support or validation, or ability to work with other women. And neither woman monitored herself regularly.”

Which came first for the successful dieters—the weight loss or the sense of efficacy and worth? “Self esteem comes with pulling the whole package together, when everything starts clicking. They’re comfortable with food, and the initial weight loss makes them feel better physically. It’s a reinforcing cycle,” Berry says.

But she tells her patients that this is a complicated process, where people make a lot of mistakes. “Nothing is black and white. It’s a gray level—it’s muddling through.”