Exercise in Your 20s to Stay Fit in Middle Age

If you think you don't need to work out just because you're slim and trim at 25, think again. A new study shows that people who start a regular fitness regimen in their 20s and stick with it into their 30s and 40s experience less middle age spread.

The study, published in the latest issue of the Journal of the American Medical Association, found that starting exercise early in life is especially good for women. Women who maintain a high intensity, regular fitness routine from their 20s onward gain 13 fewer pounds than women who are inactive or who are inconsistent in their exercise routines.

The new research comes out of Northwestern University Feinberg School of Medicine and was headed by Dr. Arlene Hankinson, instructor of preventive medicine. Her team's research followed the exercise patterns of more than 3,500 men and women, ages 18 to 30 at baseline, over the course of 20 years.

For the purposes of the study, Hankinson told AOL Health her team defined "high intensity" exercise as exercise of high frequency and duration for at least 150 minutes per week, which is in keeping with federal guidelines for exercising at least 30 minutes five days a week. "We found that 25 minutes of exercise every day is better at maintaining weight than 45 minutes a day once in awhile," Hankinson said.

So what if you're 35 or 45 and you've never engaged in regular exercise? Is it too late to start to see a benefit? Hankinson said that while her study only looked at people who started exercising in young adulthood, she would certainly encourage anyone of any age to get moving. "It's not that there are fewer benefits of activity when you start late," she explains. "It's that the amount of activity you have to do may increase."

For more on staying fit, visit AOL Health.