Maintaining High Physical Activity Level for Many Years Lessens Weight Gain Going Into Middle Age

Newswise — Young adults, particularly women, who maintained high levels of moderate and vigorous activity over a period of 20 years experienced smaller gains in weight and waist circumference during the transition from young adulthood to middle age, compared to individuals with lower activity levels, according a study in the December 15 issue of JAMA.

The prevalence of obesity has increased markedly since 1976, now exceeding 30 percent among U.S. adults, and has well-known associations with illness and disability. Although many studies have examined treatments for obesity, data supporting physical activity guidelines to prevent long-term weight gain are sparse, particularly during the period when the highest risk of weight gain occurs, according to background information in the article.

Arlene L. Hankinson, M.D., M.S., of the Feinberg School of Medicine, Northwestern University, Chicago, and colleagues conducted a study to evaluate the relationship between maintaining higher activity levels and changes in body mass index (BMI) and waist circumference over 20 years in young adults. The Coronary Artery Risk Development in Young Adults (CARDIA) study is a prospective study with 20 years of follow-up, 1985-1986 to 2005-2006. Habitual activity was defined as maintaining high, moderate, and low activity levels based on sex-specific groupings (by thirds) of activity scores at the beginning of the study. The study included 3,554 men and women, ages 18 to 30 years at the beginning of the study, from Chicago; Birmingham, Ala.; Minneapolis; and Oakland, Calif. At follow-up examinations, participants were administered questionnaires, which asked about participation in 13 specific moderate- and vigorous-intensity activities over the previous year, including sports, exercise, home maintenance, and occupational activities.

The researchers found that over 20 years, maintaining high levels of activity was associated with smaller gains in BMI and waist circumference compared with low activity levels after adjustment for race, baseline BMI, age, education, cigarette smoking status, alcohol use and energy intake. "Men maintaining high activity gained 2.6 fewer kilograms [5.7 lbs.] per year (+0.15 BMI units vs. +0.20 in the lower activity group), and women maintaining higher activity gained 6.1 fewer kilograms [13.4 lbs.] per year (+0.17 BMI units vs. +0.30 in the lower activity group). Men maintaining high activity gained 3.1 fewer centimeters [1.2 inches] in waist circumference per year (+0.52 cm vs. 0.67 cm in the lower activity group) and women maintaining higher activity gained 3.8 fewer centimeters [1.5 inches] per year (+0.49 cm vs. 0.67 cm in the lower activity group)."

The authors add that weight gains in participants with moderate or inconsistent activity levels generally were not different from the low-activity group. "Importantly, women seemed to benefit the most from maintaining higher activity; the magnitude of weight change was more than twice as large among women compared with men. Similarly, participants who maintained the Health and Human Services-recommended 150 minutes of moderate activity per week gained significantly less weight compared with participants who did not."

"These results suggest that maintaining higher activity levels during young adulthood may lessen weight gain as young adults transition to middle age," the researchers write. "Our results reinforce the role of physical activity in minimizing weight gain and highlight the value of incorporating and maintaining at least 30 minutes of activity into daily life throughout young adulthood."

(JAMA. 2010;304[23]:2603-2610. Available pre-embargo to the media at www.jamamedia.org)

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