Thinking of liposuction to trim your tummy? You may want to make sure you exercise after that, or risk putting on even more unhealthy fat.       

According to a Brazilian study, women who have liposuction may actually gain some fat deeper within the abdomen - a type of fat that's particularly unhealthy.

The researchers, led by Fabiana Benatti of the University of Sao Paolo, found that within months of abdominal liposuction, there may an increase in the so-called “visceral” fat that surrounds the abdominal organs.

But the good news is that regular exercise may prevent that deep fat from forming, they wrote in the Journal of Clinical Endocrinology and Metabolism. Fat is not “inert tissue,” Benatti told Reuters Health in an email.

“Removing it by surgery may have important consequences such as the compensatory growth of visceral fat, which may be deleterious in the long term,” she said.

Visceral fat is particularly undesirable because it's more closely connected to the risks of type 2 diabetes and heart disease compared to the superficial abdominal fat just under the skin.

The findings are based on 36 normal-weight women who had liposuction to take away a small amount of superficial belly fat. All had been sedentary before the procedure.

Benatti's team randomly assigned half of the women to start an exercise program two months after their liposuction. Those women worked out three times a week, walking on a treadmill and doing light strength training, while the rest stuck with their usual lifestyle.

Four months later, the study found, women who'd remained sedentary still had flatter bellies, but were showing a gain in visceral fat - a 10 percent increase, on average.

In contrast, women who'd been exercising showed no such gain. It's not really clear why visceral fat increases post-liposuction, Benatti said.

“But we believe it may be because this particular fat depot is more metabolically active than other fat depots,” she added.

Another reason may be because liposuction destroys the “architecture” of fat cells just below the skin, so fat regain may be redirected to still-intact visceral fat cells.

In general, experts say that liposuction should not be seen as a substitute for a healthy diet and exercise. It's also intended to reduce stubborn pockets of fat, not as a treatment for obesity, according to the American Society of Plastic Surgeons.

In fact, the group says the best candidates for liposuction are people who are normal weight to moderately overweight and already regularly exercise.

“If one should choose to undergo liposuction, it is very important, if not essential, that this person exercises after the surgery,” Benatti said.