Subjects: Behavioral health
People know it’s important to avoid excessive weight gain as they get older, and that exercise is a key to success in this regard. But until recently, scientists had published surprisingly few studies purporting to quantify the impact of habitual exercise on weight gain over the long haul.
Arlene Hankinson and her colleagues at Northwestern set out to do just that. Using data from a prospective follow-up study, Hankinson’s group showed that men who were able to maintain high activity levels over an extended period gained 6 fewer pounds, and 5 fewer centimeters of waist circumference than those in the lowest activity group. Women in the highest activity group gained 13 fewer pounds and nearly 7 centimeters less around their waists.
To reach these conclusions, the scientists examined data from the Coronary Artery Risk Development in Young Adults (CARDIA) study, which is a 20-year longitudinal study that began in 1985. CARDIA included complete historical data for 3,554 men and women from Chicago, Birmingham, Minneapolis and Oakland. Enrollees were 18 to 30 years old at study onset.
During each follow-up visit, CARDIA enrollees completed questionnaires regarding their activities and exercise habits. Each activity had been assigned a numerical score ranging from 108-288 by the scientists. Activity scores were summed for each individual to yield a total score.
The authors subsequently divided study participants into 3 tertiles according to their total score. To be assigned into a more active tertile, subjects had to qualify on points for at least 2/3 of all follow-up visits.
Remarkably, only 12% of study participants met criteria for the highest activity group. The reason, Hankinson said in an interview with USNews, is consistency. “It’s not that it’s hard to achieve high levels of activity,” she remarked. “It’s that it’s difficult to maintain them over time.”
Hankinson therefore recommends finding activities that are enjoyable. “Whatever activity you do, the whole point is that you’re doing something that you are going to maintain over a lifetime,” she explained. And vigorous activities like marathons and lifting heavy weights are not necessary to fall into that “high activity” group in Hankinson’s study. All that’s required is about 2 ½ hours per week doing things that get one’s heart rate up. So things like step aerobics, dance, speed walking and the like are perfectly adequate.
It’s also essential to note that folks in all activity groups in Hankinson’s study did gain at least some weight. The take-home message is that exercise alone isn’t going to be enough to maintain a stable body weight into and beyond mid-life. There’s simply no getting around the fact that dietary intake is the single most important factor in determining weight gain.
Hankinson’s write-up appears in the Journal of the American Medical Association.