Well, maybe it's not that surprising, but here it is: Healthier men have better sex. Lean, physically active men are less likely to have problems with erectile function than obese couch potatoes. In a new study, a group of Italian researchers wanted to find out if they could use that information to help obese men with erectile dysfunction; in the study, obese men went on a diet, got more exercise, and reported on their sex lives.

What the researchers wanted to know: Does losing weight improve erectile function?

What they did: Obese men who came to the hospital of the Second University of Naples with erectile dysfunction were recruited for the study. The study started in October 2000, when men filled out a questionnaire on erectile function and were randomly assigned to lose weight or be in a control group. Men in the weight loss group went to monthly sessions on weight loss. All the men were given various blood tests at the beginning and end of the study, which lasted two years.

What they found: The men who lost weight had higher erectile function scores at the end of the study; almost a third of them improved enough that they didn't have erectile dysfunction anymore. The more weight they lost, and the more exercise they did, the more their erections improved.

What the study means to you: Eat less, exercise more, have better sex. An earlier study suggested the equivalent of a daily two-mile brisk walk could reduce the risk of erectile dysfunction by 70 percent.

Caveats: Men who are depressed and anxious have more erectile problems, so it's entirely possible that the weight-loss group did better because the diet and exercise made them happy. But that wouldn't explain why their endothelium, the lining of the blood vessels, worked better, too.

Find out more: Erectile dysfunction from NIH: kidney.niddk.nih.gov

Read the article: Esposito, K., et al. "Effect of Lifestyle Changes on Erectile Dysfunction in Obese Man: A Randomized Controlled Trial." Journal of the American Medical Association. June 23/30, 2004, Vol. 291, No. 24, pp. 2978–2984.

Abstract online: http://jama.ama-assn.org