A guest post by Matthew Denos, PhD

Both men and women in western countries have the tendency to gain weight as they age. Age-induced weight gain is a fact we are all familiar with. It doesn’t take more than a glimpse at our parents wedding photo album or a look at the pictures of our high school graduation dance to remind us of this common reality.
People usually gain weight in various stages of their life. Professor Levitsky from Cornell found that freshmen gain an average of 4.2 pounds during their first semester on campus as a result of the all-you-can-eat dining facilities and the increased late snacks that are typically consumed by this age group [1].
Another study, published in a 2009 issue of the journal of Obesity, shows that people who get married or move in with a partner become heavier. In fact, couples face double the chances of becoming obese than singles [2].
And after a child is born, the pregnancy-gained pounds become a permanent problem for many moms.
At grandparent age, the sedentary lifestyle, usually a result of poor musculoskeletal health, increases our chances of gaining weight even more. Mobility disorders facing older people, such as osteoarthritis, have been shown to increase the risk of gaining weight [3].
Running, or jogging, is the most common type of exercise. It is safe, affordable and can be enjoyed almost anywhere. However, when it comes to weight loss, it is often dieting—not exercise—the best treatment recommended by experts. Running has always been suggested as a complement to dieting with the purpose of inducing weight loss. But can running without dieting cause weight loss? Better yet, can habitual running alone protect against the seemingly inevitable age-related weight gain?
Can Running Without Dieting Lead to Weight Loss?
Real life experiences as well as several clinical trials show that when people who lead a physically inactive lifestyle start to exercise, they lose weight and body fat. Conversely, when active individuals stop exercising, they gain weight. There is actually a direct relationship between the intensity of exercise and weight loss.
A 2006 Berkeley study examined three groups of people; people who gave up their regular running habit, either partially or totally; sedentary people who began running; and people who continued their sedentary lifestyle. No particular emphasis was given in the diet aspect of the participants’ life.
At the 7-year follow up, those who had quit running exhibited a significant increase in body weight, BMI, and waist circumference—an index of central adiposity. This increase was proportional to the decrease in their running distance. For example, at 7 years, those who reduced their weekly distances by 20 miles saw a greater increase in body weight and central adiposity than those who reduced their running only by 10 miles. In women, bra cup size increased in proportion to the decreases in running distance.
On the other hand, the sedentary group of people who started running up to 14 miles per week, experienced significant weight loss. The weight loss and waist circumference reduction were proportionate to the increases in running distance. Moreover, in the 7-year course they gained significantly lower weight than those who remained sedentary.
Other studies, involving 40,000 women runners, have confirmed these results, showing an inverse correlation between miles run per week and BMI, waist circumference and bra cup size [4].
These findings are particularly important because they show that running has direct effects on body weight, independently of dietary interventions.
Can Running Attenuate Age-Related Weight Gain?
Body weight generally increases as we age. Of course, vigorous exercise like running has the potential to produce great weight loss. An interesting question is, what is the long-term effect of running on weight gain? Can it prevent age-related weight gain?
In a rather unique study that lasted for 7 consecutive years, the participants were stratified into 3 groups based on their weekly running distances; those who maintained modest (0-15 miles per week), intermediate (16-30 miles per week) or prolonged running distances (more than 31 miles per week).
In all three categories, the average body weight, BMI and waist circumference increased over time. However, those who maintained a minimum distance of 31 miles per week experienced only half the annual increase in body weight, BMI and waist circumference than those who ran less than 15 miles weekly. In particular, women who ran consistently more than 31 miles per week gained 8 lbs less weight, and their hip circumference was 1.2 inches smaller at the end of 7 years.
Conclusion
Weight gain is an inherent component of aging—a collateral effect if you will. At the same time, increased body weight has important emotional, social, and medical consequences. Excess weight, especially in the abdominal area, has the potential to cause many serious illnesses such as diabetes, stroke and heart disease.
But even modest weight gain can be harmful. Willet and colleagues found that middle-aged women who gained weight after the age of 18, had increased risk for coronary heart disease despite the fact that their BMI never escaped the 18-25 normal range [5].
Running is a leisure type of exercise activity that most people can do. The recommendation from the National Institute of Medicine is 1 hour of walking (3 mph), or 30 minutes of running (6mph), to maintain healthy weight, every day. Research shows that running, as a therapeutic strategy, has the potential to not only prevent short-term weight loss but also attenuate long-term weight gain.
About the Author:
Guest author Matthew Denos, PhD, is a biology scientist and advocate of the benefits of running for weight loss and overall good health. He enjoys writing about research findings in the field of nutrition, exercise and weight loss programs and offers a
promo coupon for Medifast (a clinically studied medical diet plan) and a
discount for DiettoGo, a dietitian-designed meal delivery program.
References
1. http://cornellsun.com/node/31846
2. http://www.telegraph.co.uk/news/newstopics/howaboutthat/5507729/Getting-married-or-moving-in-with-a-partner-will-make-you-fat-new-research-shows..html
3. Most patients gain weight in the 2 years after total knee arthroplasty: comparison to a healthy control group. Zeni JA Jr, Snyder-Mackler L. Osteoarthritis Cartilage. 2010 Apr;18(4):510-4. Epub 2009 Dec 21
4. Relationships of age and weekly running distance to BMI and circumferences in 41,582 physically active women. Williams PT, Satariano WA. Obes Res. 2005;13:1370–80.
5. Weight, weight change, and coronary heart disease in women. Risk with the “normal” weight range. Willett WC, Manson JE, Stampfer MJ, et al. JAMA 1995;273:461–465.