Is it better to have lost weight and regained it than never to have lost it in the first place?

If you're a chronic dieter, a yo-yoed, a "weight cycler," the short answer is probably yes.

If the weight loss is healthy — done slowly with nutritious foods, exercise and the right attitude — you'll still benefit in the long run, said Weight Watchers chief scientific officer Gary Foster.

All that stuff you've heard or imagined over the years — that the fat moves from your butt to your belly, that you'll regain more weight every time you give up on a diet, that you're better off just giving in to the weight than trying over and over again? "It's all mythology," Foster said.

Of course, every weight-loss effort isn't healthy. And that's where weight cyclers run into trouble, said Dr. Maurice Bonilla, a doctor of bariatric medicine based in Tampa.

"It depends on the diet," he said. A medical plan designed and monitored by a physician is safer than a fad that depends on some magical ingredient — grapefruit, cabbage, cookies, baby food — that desperate dieters latch onto, hoping for quick and easy results. Those diets often do have negative impacts.

If you're losing too fast, you may not be losing as much fat as you hoped, and you might be losing lean tissue. Your body will slow its metabolism to reserve incoming calories. You could even damage your heart, kidneys and other organs. (The Mayo Clinic recommends that any rapid weight-loss program be monitored by a physician.)

If you're overdoing it with your workout, with too much exercise and too little nutrition, you can end up putting your body in starvation mode. It makes losing harder, and you'll feel irritable and fatigued.

Foster said people often develop an all-or-nothing attitude about dieting. They make their weight a moral issue that requires blame and punishment. "It's only going to take one slip or two, and all hell's going to break loose and you're going to end up right back where you were," he said.

Fitness trainer and nutrition specialist Debbi Doughty-Lewis agreed that emotions play a major role in dieting. "We let ourselves down when we fall off the wagon, and we beat ourselves up," she said.

Anger, disappointment, embarrassment — she has seen the full range of emotions from clients who have slipped. And as a former weight cycler, she has experienced them herself.

Foster said that even a short-term weight loss has physical benefits.

"I think the science is pretty clear," he said. Every organ "is adversely affected by excess body weight. There's not an exception. Once you have that knowledge, you have to say, 'OK, if I can decrease my risk by decreasing my weight, and I don't have the guarantee that it will stay off forever, would I still do it?' I think the answer is a clear yes."