For many veterans of crash diets, killer workouts and tailored meal plans, weight loss surgery is the nuclear option in a battle against the bulge.
But while such procedures can indeed lead to dramatic weight loss, for some the pounds return.
Such appears to be the case with musical star Carnie Wilson, whose fluctuating figure dominated tabloid front pages this week in the latest chapter of her widely publicized fight against obesity since her gastric bypass surgery in 1999.
Wilson, 31 at the time, weighed more than 300 pounds before the procedure that reduced the size of her stomach to that of an egg.
Speaking with ABC's "20/20" at the time, Wilson said that at that weight she felt "tired a lot, I'd feel sluggish. I started getting paranoid. ... I felt like I was going to have a heart attack."
By all accounts, Wilson's procedure was a success; she dropped 152 pounds and her new trim figure soon made her the poster child of weight loss surgery.
She regained 70 pounds in 2005, when she was pregnant with her daughter, but later lost the weight. Until recently she sported a trimmer figure.
But that appears to have changed. New photos released by the celebrity Web site TMZ.com Tuesday show the singing star significantly heavier than before.
When the Pounds Come Back
Without a doubt, weight loss surgery works. Within the first two years of surgery, most patients who have such procedures can expect to lose 50 percent to 80 percent of their excess weight.
This means that if a patient's ideal weight is 150 pounds and they weigh 350 pounds, they can expect to lose between 100 and 160 pounds in those first two years. And following suggested lifestyle modifications, most of which revolve around healthy diet and regular exercise, can go a long way in ensuring that this weight stays off.
But for some, like Wilson, the weight can come back.
"We know that 5 percent or maybe even more of these patients over time can regain weight," said Dr. Daniel Jones, director of the bariatric program at Beth Israel Deaconess Medical Center in Boston. "A large part of that has to do with the fact that the factors that caused them to be overweight to begin with are still out there."
And while a few patients regain a large percentage of their original weight back, Dr. Anita Courcoulas, chief of minimally invasive bariatric and general surgery at the University of Pittsburgh Medical Center, says that most of those who have gone through the surgery will experience some weight gain after the bulk of their post-surgery loss.
"Most patients experience something I call 'the creep,'" she said. "They creep up another five to 10 pounds. Eighty percent will experience this creep and level out again, but about 20 percent will continue to creep up."
It turns out that caloric restriction is just one part of the equation, although a large part. And reducing the space in your stomach into which your meals can fit to the size of a large walnut is a particularly effective way to cut hunger and jump-start weight loss for morbidly obese individuals.
The most rapid phase of weight loss after surgery occurs during the first year. After this, the rate of weight loss will slow. And after two years, the patient has reached a new "set point" in terms of weight.
From here, biology can reassert itself. Courcoulas says the tiny pouch that serves as the new stomach expands slightly in most patients, perhaps increasing in size between 10 percent and 15 percent. If a stretch of intestine has been removed through surgery, the remaining portion may become more efficient in absorbing calories. For most, these changes result in just a slight "bounce" to a modestly higher weight.
But for some, this plateau period represents a danger zone. If a patient's eating and exercise habits have evolved, they can maintain this new weight. But if they have not, excess eating can cause what remains of the stomach to stretch significantly to accommodate more food -- thus leading to weight gain.
"If you tend to keep pushing yourself, taking one extra bite with every meal, then you can stretch the pouch," Jones said. "Over time you will eat more and more."
But Jones notes that more of a threat than the re-expansion of the stomach is simply eating too much of the wrong foods -- high-sugar, high-fat treats that pack a caloric punch sufficient to bring the weight back.
The Psychological Side of Weight Maintenance
For this reason, counseling and other forms of psychological support are often seen as key to reaping the long-term health gains of weight loss surgery.
These benefits go far beyond a more attractive figure. For many morbidly obese patients, having such surgeries and maintaining a more normal weight can have a significant impact on their overall health and risk of early death.
"It is very important for these patients to receive behavioral therapy, as well as time with a nutritionist and a physical therapist," Jones said. "I can cut and sew, but it's really the nutritional and behavioral programs that help with patient success."
And along with professional help, maintaining personal motivation to keep the weight off is crucial.
"These are people who feel that they have failed at everything they tried in their lives," Courcoulas said. "If they feel that they are failing surgery, they're embarrassed and they don't want to come back for help."
"Regaining weight down the road is a common phenomenon for weight loss patients. These patients need to be educated and prepared for it if it happens."