CHICAGO --- People will gain significantly less weight by
middle age – especially women – if
they engage in a vigorous activity five days a week starting as young adults,
according to new Northwestern Medicine research.
Women particularly benefitted from high activity over 20
years, gaining an average of 13 pounds less than those with low activity; while
men with high activity gained about 6 pounds less than their low-activity
peers. High activity was defined as an occupational activity such as housework
or construction work or recreational exercise (basketball, running, brisk
walking or an exercise class) for 30 minutes, five times a week.
“Everyone benefits from high activity, but I was surprised
by the gender differences,” said lead author Arlene Hankinson, M.D., an instructor
in preventive medicine at Northwestern University Feinberg School of Medicine.
“It wasn’t that activity didn’t have an effect in men, but the effect was
greater in women.”
The study was published Dec. 14 in the Journal of the
American Medical Association.
There could be several reasons for the gender difference,
Hankinson said. Women are less likely than men to overestimate their activity, according
to previous studies. “Men may not
be getting as much activity as they report,” Hankinson explained.
In addition, men in the high activity group compensated by
eating more than their low-activity counterparts, which could have led to more weight
gain. The highly active women didn’t eat more than low-activity women in the
study.
This study was part of the Coronary Artery Risk Development
in Young Adults (CARDIA) Study, a multi-center, longitudinal, population-based,
observational study designed to describe the development of risk factors for
coronary heart disease in young black and white adults recruited from four
geographic areas in the United States: Birmingham, Ala..; Chicago; Minneapolis;
and Oakland, California.
"This paper is another example of how the CARDIA study
has contributed to our knowledge about the importance of initiating healthy
habits early in life and vigilantly maintaining them. Common medical problems such as heart disease, diabetes, and
obesity have their origins in childhood and can generally be prevented by maintaining a
normal weight, not smoking, exercising regularly, and eating a healthy diet
throughout life,” said coauthor Stephen Sidney, MD, MPH, Associate Director for
Clinical Research at the Kaiser Permanente Division of Research.
The study of 1,800 women and nearly 1,700 men is the first
to measure the impact of high activity over 20 years between young adulthood
and middle age and to frequently examine participants (seven
times) over that period. Study participants are more likely to remember and accurately
report their behavior with regular exams, Hankinson noted.
Previous studies, Hankinson said, looked at a single
exercise intervention’s effect on weight for a short period of time, or examined
participants at only two points in time – the beginning and the end – of longer
studies.
“We wanted to see if people’s activity levels of their youth
were enough to help them keep weight off in middle age, or if they needed to up
the ante,” Hankinson said. “It’s difficult to avoid gaining weight as you age.
Our metabolic rate goes down. We develop conditions or have lifestyles that
make it harder to maintain a high level of activity.”
Moderate activity and low activity had the same negligible
affect on weight gain in the study. “Vigorous activity was the only kind that made
a significant difference,” Hankinson noted.
“The study reinforces that everyone needs to make regular
activity part of their lifestyles throughout their lives,” Hankinson said. “Not
many people actually do that. Women should be especially motivated.”
The active group in the study comprised only 12 percent of
the participants.
The CARDIA study is sponsored by the National Heart, Lung
and Blood Institute. The
participants were 18 to 30 years at the beginning of the study and 38 to 50 at
the end. are currently undergoing a 25-year follow-up examination at ages 43 to
53 years.
