It can happen to the best of us: You decide you want to lose weight and you successfully drop some pounds. But you go back to your old eating habits or gorge on the foods that you’ve been craving for whatever reason, and suddenly the scale’s telling you you’ve gained everything back, maybe even more. Eventually, you start trying to lose the weight again…

“Yo-yo” dieting is the everyday term for when people lose weight and gain it back, sometimes again and again over many years.

“It’s a very common pattern,” said Christine Tenekjian, a registered dietitian at the Duke Diet and Fitness Center in Durham. “Sometimes it’s just 20 pounds at a time and they might regain 25, but sometimes it’s 50 or 100 pounds, then regaining more than that.”

Nationally, research has shown many people who lose weight manage to keep it off initially. But findings show that over several years, they often gain weight back.

Susan Pflug, 65, of Charlotte, has been trying to lose weight – and then keep the pounds off – for more than 20 years.

Part of it had to do with appearance, but mostly she wants to maintain her health. Around the time her father died, her outlook shifted. She says she became more aware of mortality and time passing.

Pflug, a retired librarian, has had no weight-related health issues so far, but she knows there’s no guarantee her health will last forever.

She also wants to dance with her husband without her feet hurting, and to have more energy to keep up with her grandchildren.

“I am absolutely worn out at the end of” visits, she said, laughing. “I would like that to change.”

Over the years, Pflug has tried Weight Watchers, the Atkins Diet and giving up fat, among other things. She says some diets work well for losing weight, if you can stick to them.

In the past, she’s dropped 65 pounds, then gained 30 back. “It’s extremely frustrating,” she said.

Why does it happen?

Nutritionists and dietitians say a few key factors often contribute to yo-yo dieting, including quick-fix diets and stress.

Some diets lead people to adopt a radically different approach from their typical eating pattern, like cutting out an entire food group. While it can lead to weight loss in the beginning, it also makes it easy to revert to old eating habits, and maybe even binge.

“Changing behavior is not an easy task,” said dietitian Manuel Villacorta, a spokesman for the Academy of Nutrition and Dietetics and creator of the “Eating Free” weight-loss program.

A 2011 study in The New England Journal of Medicine suggests there could be physiological reasons that explain why obese people often regain weight.

Researchers found that weight loss through diet is associated with an increase in a hormone that stimulates hunger. Those urges to eat can last for at least a year after the loss. Dietitians stress that stable weight loss comes with a lifestyle change, not a quick fix.

“It’s not a sexy approach,” Tenekjian said. “… You’ve just got to adopt a lifestyle change and figure out how it’s going to work in the context of your life. People don’t like that… They want a quick fix, and that’s why, I think, yo-yo dieting is so common.”

Elaine Jones, clinical nutrition manager at Carolinas Medical Center-University, typically has clients set goals of 10 percent weight loss over six months. In that time, they can learn behavioral changes and practice them.

“It’s the routine that creates the habit, that creates the long-term stability and maintenance of that weight loss,” Jones said.

Villacorta says people should learn to incorporate and balance foods that they enjoy into their diets because if they try to cut them out entirely, it can be a recipe for failure.

“I always say that willpower is like an elastic band,” he said. “You just keep pulling and pulling and it just gets weaker and weaker with time … and then you break, and that’s the problem with restrictions.”

Eat food you like

Instead of cutting some foods out completely, Villacorta suggests looking into proper portioning and how to balance meals throughout the week.

For some, stress can lead to on-again, off-again dieting if they see eating as a way to deal with their emotions.

“If you don’t really ever tackle that, (you’re) never going to win the war,” he said.

Tenekjian says her No. 1 tip for people trying to lose weight is to think about where they are now and to pick one or two things to do that can help improve eating or exercise habits. If stress is an issue, she says, maybe start there.

Pflug, of Charlotte, says stress has derailed her weight loss in the past.

“Every time we would go through a crisis of any kind, I would binge-eat and gain back whatever I had lost and plus some. And so it would be an up-and-down, up-and-down, up-and-down thing.”

Pflug, 5-feet-4, has lost weight from her heaviest at about 250 pounds. She is now about 220 pounds and would like to get down to 150.

Pflug works out three to four times a week for about an hour. She’s not on a prescribed diet right now, but she’s trying a self-hypnosis CD that suggests changes in eating behavior, like eating only when she’s hungry or laying down utensils between bites. She says she’s almost stopped saying the word “diet.” She thinks instead about better food choices and habits.

It’s been a long road, but Pflug stays motivated. “I haven’t given up yet, and I don’t expect I ever will, because I really do want to be healthy and have more energy.”