Many people develop stubborn fatty deposits — like in the buttocks or upper thighs, or the so-called "love handles" — that are resistant to dieting and exercise. And although most people would admit to wanting to reshape their body in some way, not everyone makes an ideal liposuction candidate, says Daniel Morello, M.D., president of the American Society for Aesthetic Plastic Surgery. Morello stresses that liposuction is for body contouring, not weight reduction. "It is designed for removing localized areas of fatty tissues — not as a substitute for proper dietary management and exercise."

But what happens to the mildly to seriously overweight people who want and get liposuction? Sometimes after the surgery, these people may face yet another unwanted — and possibly unexpected — complication: the return of fatty deposits.

But probably in other areas of the body, says C. Wayne Callaway, M.D., an associate clinical professor of medicine at George Washington University. Callaway, who is also an internist, endocrinologist, and obesity specialist in Washington, D.C., sees post-liposuction patients complaining of renewed accumulations of fat.

Animal studies have shown that if you remove significant amounts of fat from one area, body fat increases elsewhere, according to Callaway. "The signal is leptin, a hormone made in fat cells," he says. "The more fat you have, the more leptin is made...and if a large amount of fat is removed, there is a drop in leptin levels." In animal studies, this drop in leptin levels results in an increase in food intake and a decrease in activity until the leptin levels are up again, according to Callaway.

Callaway says that the people who have the most trouble after a liposuction procedure are the really obese who have had large amounts of fat removed. "They have a compensatory increase in new fat cells," Callaway says. "And fat goes to areas where there are still a lot of fat cells. So that means to the neck, above collar bones, and the upper abdomen."