NEW YORK (Reuters Health) – Metabolic syndrome, a cluster of conditions that increases the risk of heart disease, stroke and diabetes, in extremely obese patients can be cured by gastric bypass surgery, according to the findings from a new study.

"Reversibility of metabolic syndrome depends more on the percentage of excess weight lost than on other clinical or demographic characteristics," the research team reports in the journal, Mayo Clinic Proceedings.

To determine the effect of major weight loss on the metabolic syndrome, Dr. Francisco Lopez-Jimenez and colleagues evaluated patients being considered for bypass surgery at the Mayo Clinic in Rochester, Minnesota, between 1990 and 2003.

All patients met at least three of the five criteria for the metabolic syndrome – high levels of triglycerides (a "bad" fat), low levels of high-density lipoprotein "good" cholesterol, increased blood pressure, high blood sugar levels and obesity.

The study group included 180 patients who underwent gastric bypass and 157 patients who did not undergo the procedure, either because they declined surgery, were denied coverage by insurance providers, or did not maintain lifestyle interventions during their evaluation. All patients received medical and dietetic care and extensive counseling about the importance of physical activity.

The mean body mass index (BMI) was 49 in the surgical group and 44 in the nonsurgical group. A normal BMI is considered to be between 18.5 and 24.9.

During an average follow-up of 3.4 years, the prevalence of metabolic syndrome decreased from 87 percent to 29 percent in the surgical group, and from 85 percent to 75 percent in the control group. The authors estimate that the number of patients needed to treat with bypass surgery to cure one patient of metabolic syndrome was 2.1.