All Credits goes to Carin Gorrell

You've lost the weight. Here's how to stay fit.

What's harder than trying to lose weight? Keeping the pounds off. And unfortunately, research on the probability of maintaining weight loss is not always encouraging.

"The most difficult part of maintaining weight loss is sticking to what got you there," says Kerri Plum (name has been changed), a human resources representative who has made three unsuccessful attempts at reaching and maintaining her goal weight since attending college. "When the weight is gone, it's hard not to think, 'Hey, I deserve dessert tonight or a bag of chips with lunch today.'"

More than 56 percent of adults in the U.S. are overweight or obese, according to a study published in the Journal of the American Medical Association. Despite Americans' sincere efforts—more than 54 million are dieting—the nation's obesity rate continues to rise. Of those who do successfully lose weight, 90 to 95 percent are unable to keep it off long-term. This is a particularly disconcerting statistic considering the numerous physical and mental-health problems that accompany being overweight, including an increased risk of developing diabetes, heart disease and depression.

That said, take heart: A number of people do beat the odds, and experts are attempting to learn their secrets. In the past, few studies examined methods for long-term success, a void that inspired doctors at the Universities of Colorado and Pittsburgh to devise the National Weight Control Registry (NWCR). Founded in 1993, the NWCR was designed not to help people lose weight but to study adults who have already dropped 30 pounds or more and kept it off for one year.

"People lose weight all the time, but keeping it off seems to be the difficult part," explains Holly Wyatt, M.D., an endocrinology professor at the University of Colorado (CU) who conducts research with NWCR co-founder Jim Hill, Ph.D. "We're really more interested in weight maintenance than in initial weight loss," adds Wyatt.

Thus far, Wyatt and other NWCR researchers have discovered four distinct behavioral trends among the registry's nearly 3,000 participants. First, regardless of the diet they followed to lose weight, most participants now eat a low-fat, high-carbohydrate diet. They also make sure to eat breakfast—almost 80 percent do so seven days a week.

In addition to monitoring diet, registrants regularly engage in high levels of activity to remain slender. They report burning an average of 2,800 calories per week each, which is roughly equivalent to walking four miles a day. Of course, people tend to overestimate their activity levels, so Wyatt asked participants to wear pedometers, instruments that count the number of steps a person takes. She also gave pedometers to people who had visited CU's clinic and wished to lose weight but hadn't yet started a weight-loss program.

After comparing tallies, Wyatt discovered that those who were overweight and hadn't changed their habits took significantly fewer steps than did their thinner counterparts, averaging only 5,000 steps per day compared with those in the registry who were taking 11,000 daily steps. "Other studies report that physical activity is the best predictor of long-term weight maintenance," Wyatt says. "This agrees with what our registry people are telling us." Her findings were presented to the National Association for the Study of Obesity.

Finally, successful weight-loss maintenance seems to require consistent "self-monitoring." For instance, some NWCR participants weigh themselves daily, while others keep a precise food journal. "They're always watching for changes and respond to them quickly," Wyatt says. "They don't just let things go." Whatever the method, self-monitoring requires the same restraint and vigilance—what some experts refer to as "cognitive control"—as does committing to a weight-loss program.

"Cognitive control plays a big role," Wyatt notes. "But it doesn't mean that if you have a weight problem you don't have control. It's harder for certain people than for others; that may be where genes and physiology come in."

Not surprisingly, cognitive control is also key in losing weight, a struggle that varies in difficulty among individuals and genders. One national survey by the Calorie Control Council (CCC) found that 41 percent of women blamed weight loss failures on lack of self-discipline, and 36 percent admitted they eat for emotional reasons. In comparison, only 30 percent of men attributed an inability to lose weight to low self-discipline, and they were half as likely as women to eat emotionally. So while women are more prone to cite internal reasons for their failures, men point to external factors such as eating improperly at restaurants.

Despite differing opinions on the challenges of losing weight, men and women do agree on what is necessary to win: Both genders say it takes long-term lifestyle changes, not short-term fad diets. In fact, the majority of men and women surveyed by the CCC named exercising, consuming foods and drinks low in fat and sugar, eating smaller-portioned meals and combining calorie reduction with physical activity as the most popular methods for losing and controlling weight.

Ultimately, it appears there is no magic pill for keeping trim. Instead, the old adages prove true once again: Everything in moderation; live healthy, look healthy. But while making lifelong behavioral changes can be daunting, there is some reassuring news:

"People who have maintained their weight loss for three to five years say it gets easier," Wyatt says. Jeffrey Kluger, a Time magazine senior writer, agrees. And he speaks from firsthand experience.

"It really has gotten easier," says Kluger, who lost 20 pounds in 1985 and kept it off through both dieting and exercise. "I find the reward for remaining vigilant in the long run is much greater than the short-term gratification of indulging."