To preserve your sexual health, keep your pants size at 40 or below, and take walks on your lunch breaks.

Well, no wonder there’s no Santa junior.

RODALE NEWS, EMMAUS, PA—If your waistline exceeds 40 inches, and you’re one to ride the escalator rather than walk the stairs, your sex life could be paying the price, according to a new study published in the Journal of Sexual Medicine.

THE DETAILS: Researchers sifted through data on nearly 4,000 men, and found that a high waist circumference (more than 40 inches) or an obese body mass index (BMI of 30 or more) was linked to a 50 percent higher risk of having erectile dysfunction (ED), compared to those with a smaller waistline or a normal-range BMI. Moderately active or inactive men (those doing less than 150 minutes a week of physical activity) faced 40 to 60 percent greater odds of ED, compared to the active men. Researchers concluded that regardless of BMI, getting 150 minutes a week of moderate physical activity, such as brisk walking, and keeping your waist size at or below 40 inches, are both associated with healthy erections (no Viagra required).

WHAT IT MEANS: About 30 million men in the United States have erectile dysfunction; this study shows that number could shrink if men’s waistlines do. And that’s on top of the other benefits of losing weight, such as reductions in the risks of heart disease, diabetes, heart attack, and cancer.

Here are some strategies for shrinking your waist size: