Aging Women Need More Exercise Than Thought Just
to Maintain Normal Weight
Suggests 2008 federal recommendation for 150
minutes per week of exercise, lowers the risks of
chronic diseases, but is insufficient for weight gain prevention see
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March 24, 2010 A study of older women half were
age 55 or older found that it takes these women on a usual diet
approximately 60 minutes a day of moderate-intensity activity just to
maintain a normal weight. The study in the Journal of the American
Medical Association also found physical activity was associated with
less weight gain over 13 years only among women of normal weight.
"These data suggest that the 2008 federal
recommendation for 150 minutes per week, while clearly sufficient to
lower the risks of chronic diseases, is insufficient for weight gain
prevention absent caloric restriction, according to the report in the
March 24 issue of JAMA.
Physical activity was inversely related to weight
gain only among normal-weight women; among heavier women, there was no
relation, emphasizing the importance of controlling caloric intake for
weight maintenance in this group."
The prevalence of overweight and obesity in the
United States has increased dramatically over the past 2 decades, with 1
in 3 adults currently obese.
"Because the average U.S. adult gains weight with
age, developing ways to prevent unhealthful weight gain would help them
avoid having to lose weight and then trying to maintain that loss.
Compared with the vast body of research on the treatment of overweight
and obese individuals, little research exists on preventing weight
gain," the authors write.
"The amount of physical activity needed to prevent
long-term weight gain is unclear."
The study by I-Min Lee, M.B.B.S., Sc.D., of Brigham
and Women's Hospital and Harvard Medical School, Boston, and colleagues
examined weight changes associated with different physical activity
levels that included 34,079 healthy U.S. women who consumed a usual diet
(average age, 54. years) from 1992-2007.
At the beginning of the study and at years 3, 6, 8,
10, 12 and 13, women reported their physical activity and body weight.
Women were classified as expending less than 7.5, 7.5 to less than 21,
and 21 or more metabolic equivalent hours per week of activity at each
time. Analyses examined physical activity and weight change over
intervals averaging 3 years.
Women gained an average of 5.7 lbs. throughout the
study. Compared with women expending 21 or more MET hours per week,
those expending 7.5 to less than 21 MET hours per week gained .2 lbs.,
whereas those expending less than 7.5 MET hours per week gained .3 lbs,
a difference that was not statistically significant.
"There was a significant interaction with body mass
index (BMI), such that there was an inverse dose-response relation
between activity levels and weight gain among women with a BMI of less
than 25 but no relation among women with a BMI from 25 to 29.9 or with a
BMI of 30.0 or higher.
A total of 4,540 women (13.3 percent) with a BMI
lower than 25 at study start successfully maintained their weight by
gaining less than 5.1 lbs. throughout. Their [average] activity level
over the study was 21.5 MET hours per week ([approximately] 60 minutes a
day of moderate-intensity activity)," the researchers write.
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