Many people remember young adulthood as a carefree time when they could eat almost anything without packing on extra pounds. But a new study shows that regardless of diet, young adults who aren’t aerobically fit are nearly three times more likely to develop diabetes when they reach middle age.

The Centers for Disease Control and Prevention estimates that one in four Americans aged sixty years and older have diabetes. Millions more are at increased risk for the condition but have not yet been diagnosed.

To better understand the risk factors for adult-onset diabetes, Northwestern University researchers collected information from nearly four-thousand healthy young adults over a twenty-year period. Aerobic fitness was determined at the beginning, middle and end of the study period by measuring each participant’s endurance on a treadmill.

The results reveal that aerobic fitness during young adulthood decreases the risk of diabetes by two- to three-fold. The scientists found that exercise is important but it’s not everything… aerobic fitness is most beneficial when it reduces body fat. So if two people are equally as fit, the person with the higher body fat content is at increased risk for diabetes.

The study also finds that eighteen- to thirty-year-old women and African Americans are less likely than men and white adults to be aerobically fit, and are at greater risk for diabetes later in life.

So remember: If you want to live long and prosper, you’ll need to eat well and exercise.