There is more evidence linking a brisk, daily walk with a trimmer waist and a lower risk of diabetes, heart disease or stroke.

It comes from Duke University Medical Center where investigators charted exercise’s impact on 171 middle-aged, overweight men and women.

None exercised before joining the federally-funded study. Forty-one percent of the volunteers also suffered from metabolic syndrome, an umbrella term that includes high blood pressure, high blood sugar, poor cholesterol levels and a large waist. The syndrome is associated with an increased risk of developing heart disease, stroke and diabetes.

After eight months of exercise, the percentage of volunteers with metabolic syndrome fell to 27 percent. Their waistlines also shrank.

Volunteers who walked just 30 minutes a day, six days a week enjoyed the benefit. “That’s about 11 miles per week. And our study shows that you’ll benefit even if you don’t make any dietary changes,” noted Dr. Johanna Johnson, the study’s lead author and a clinical researcher at Duke.

The work appears in the Dec. 17 issue of the American Journal of Cardiology.