Liposuction is no substitute for dieting when it comes to preventing diabetes, hypertension and heart disease, according to researchers at Washington University School of Medicine in St. Louis
Reporting in the June 17 issue of The New England Journal of Medicine, the Washington University team found that removing abdominal fat by using modern liposuction techniques did not provide the metabolic benefits normally associated with similar amounts of fat loss induced by dieting.
Excess abdominal fat is associated with a defect in insulin's ability to regulate sugar and fat metabolism, which can lead to metabolic diseases such as type 2 diabetes, abnormal blood lipids, hypertension and heart disease.
"Despite removing large amounts of subcutaneous fat -- about 20 percent of our subject's total body fat mass -- there were no beneficial medical effects," says Samuel Klein, M.D., the Danforth Professor of Medicine and Nutritional Science, and the study's principal investigator. "Had these subjects lost this much fat by dieting, we would have expected to see marked improvements in insulin sensitivity and other risk factors for heart disease."
Klein and colleagues studied 15 obese women with excessive abdominal fat -- eight with normal glucose tolerance and seven with type 2 diabetes -- before abdominal liposuction and again 10 to 12 weeks after surgery.
The sensitivity of the liver, muscle and fat tissue to insulin was measured by performing an insulin clamp procedure. The clamp technique allows scientists to measure insulin's major metabolic effects, such as how well insulin suppresses liver glucose production and fat breakdown and how well insulin stimulates glucose uptake by muscle tissue. The researchers also measured triglyceride and cholesterol levels, blood pressure and other risk factors for heart disease.
"It was remarkable how similar the results were before and after the procedure," Klein says. "There were no changes in insulin sensitivity, blood lipids, blood pressure, or inflammatory markers associated with coronary heart disease in any of our study subjects."
On the plus side, the study did demonstrate it was possible to safely remove large amounts of fat.
"We confirmed that it is possible to do large-volume liposuction safely," says co-investigator V. Leroy Young, M.D., a private practice physician and former professor of plastic and reconstructive surgery at Washington University. "In the past, we usually removed no more than about 5 liters of fat, but in this study we showed you can safely remove four times that amount."
Although liposuction does not have beneficial medical effects, the study does provide important clues about how diet-induced weight loss improves health and lowers the risk of diabetes and heart disease.
"Liposuction surgery removes entire fat cells located under the skin but doesn't reduce the size of remaining fat cells or decrease the fat that accumulates in other tissues, such as muscle tissue, the liver and the heart," Klein says. "It may be necessary to shrink fat cells and reduce fat content in other key tissues.
"This study underscores the need for the 'old-fashioned' method of eating less and exercising more to treat obesity. The metabolic benefits of weight loss seem to be related to achieving a negative energy balance -- consuming fewer calories than you burn -- rather than simply eliminating fat cells by liposuction."