Liposuction may let doctors extract body fat, but it doesn’t trim the risk of heart disease or diabetes the same way losing weight would, researchers at Washington University School of Medicine in St. Louis reported.

Although volunteers lost 12 percent of their body weight - most of it fat tissue - their blood pressure, insulin levels, cholesterol levels and other risk factors for heart and blood sugar problems remained unchanged.

“They’re still obese. But had they lost that same amount of weight by dieting, they would have exhibited considerable improvements in their cardiovascular risk factors,” Samuel Klein, director of the university’s Center for Human Nutrition, told Reuters.

The finding means liposuction is no substitute for weight loss produced by diet and exercise, he said.

Liposuction is performed on nearly 400,000 people in the United States each year, making it the most common cosmetic operation in the country.

Not a substitute for diet and exercise
Because the risk of heart disease and diabetes is tied to the amount of body fat a person carries, some doctors had suggested that liposuction might reduce those risks.

But the new study in Thursday’s New England of Medicine has dashed those hopes.

It “provides useful objective evidence that even large-volume liposuction has little effect on insulin sensitivity or cardiovascular risk factors,” said David Kelley of the University of Pittsburgh Medical Center, in a Journal editorial.

Although liposuction reduces the number of fat cells in the body, it doesn’t reduce the plumpness of the remaining cells. Klein said it now appears that the size of the fat cells may be more important than previously recognized.

“It may be necessary to shrink fat cells and reduce fat content in other tissues,” he said.

“It is striking that the amount of fat loss achieved by liposuction in our diabetic and nondiabetic subjects did not improve any of these metabolic outcomes,” such as reducing blood pressure, the researchers wrote.

The average weight among the eight volunteers with no diabetes went from 220 pounds down to 206 pounds and they lost nearly 6 inches off their 44-inch waistline. For the seven patients with diabetes, about 17 pounds of fat tissue and 5 inches was removed from their waistlines, but they still had bellies averaging 43 inches.

Klein said the authors of earlier studies might have been misled into thinking the liposuction had broader health benefits because people who have the surgery often take other steps to further reduce their weight, steps that might cut the risk of heart disease and diabetes. It was that supplemental weight loss effort that probably produced the health benefits.

“This study is definitive,” said Klein. “After liposuction, people tend to change their lifestyle. When we prevented that from happening, we showed there was no metabolic benefit for liposuction.”