- TUESDAY, Sept. 9 (HealthDayNews)
-- Studies showing that women who exercise more and eat less lose weight
hardly seem the stuff of big headlines, but new research puts some fairly
precise numbers about physical activity and calories into the equation.
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- The new study finds women needn't engage in vigorous
exercise to reap the weight-loss benefits, provided they also watch what
they eat.
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- "There is currently a controversy over the amount
of exercise you need," says study leader John M. Jakicic, director
of the University of Pittsburgh Physical Activity and Weight Management
Research Center. "Some people say this number, some people say that
number. This is the first big clinical trial to address the issue."
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- So here are the numbers, as reported in the Sept. 10
issue of the Journal of the American Medical Association: "If you
can get people to exercise 30 minutes a day and reduce calorie intake by
20 percent, you get a reasonable reduction in weight," Jakicic says.
"If you increase that to 60 minutes a day, you dramatically increase
weight loss."
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- And while the effects of weight reduction on the risk
of conditions such as heart disease and diabetes are obvious, another report
in the journal adds a less well-known benefit: a lessened risk of breast
cancer.
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- For those women who are not exercise-prone, the good
news from the Pittsburgh study is that a brisk 30-minute walk every day
fills the bill, Jakicic says: "While 60 minutes gives better results,
30 minutes is pretty good."
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- But here's the catch: Exercise alone doesn't do it. "If
you do exercise without a change in eating habits, you won't see the benefit,"
Jakicic says.
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- But there is something of a bright tinge to that finding,
he adds. It's the amount, not the kind, of food you eat that matters: "It's
really about the calories. Anything you do to reduce calories is good."
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- Those numbers come from a two-year study of 201 non-exercising,
chubby women, average age 37, average body mass index of 32.7, which translates
to a body weight of 192 pounds for someone 5-foot-4.
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- All the women were told to reduce their food intake,
to between 1,200 and 1,500 calories a day, with fatty foods only 20 percent
to 30 percent of the diet. Then they had one of four exercise regimens
prescribed, from vigorous intensity/high duration to moderate intensity/moderate
intensity, which translates to a brisk 30-minute walk every day. After
a year, the average weight loss for those who worked hardest was 19.6 pounds,
and for those who did the minimum was 13.9 pounds.
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- Jakicic looks at that last number as encouraging. "It
is realistic to get overweight, sedentary women to do 30 minutes of exercise
a day," he says. On the eating front, the recipe is simple: "Put
what you normally put on your plate, and then reduce that by 20 percent."
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- The benefit of exercise in reduced risk of breast cancer
is outlined in a study by Dr. Anne McTiernan and colleagues at the Fred
Hutchinson Cancer Research Center in Seattle. It is a big study, looking
at exercise patterns of more than 74,000 women.
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- Again, a good benchmark was a daily brisk walk, adding
up to between 75 and 150 minutes a week. Women who walked that much lowered
their breast cancer risk by 18 percent, compared to women who did no exercise.
More vigorous exertion, up to 10 hours of walking a week, reduced the risk
slightly more. Starting exercise early in life gave the most benefit, but
women of all ages benefited -- and the greatest benefits were found in
the thinnest women.
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- This is not startling news, says Dr. Rachel Ballard-Barbash,
associate director of the National Cancer Institute applied research program,
because a review published last year found more than two dozen studies
showing "convincing evidence that physical activity protects against
breast cancer."
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- But one reason why this new study is important is that
it provides evidence that exercise at any age is good, she says: "Many
women between the ages of 50 and 79 saw benefits."
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- The mechanisms of protection appear clear, says Dr. I-Min
Lee, an associate professor of medicine at Harvard Medical School who wrote
an accompanying editorial.
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- "Weight reduction favorably alters estrogen levels
in the body," Lee says. "It also affects insulin and growth factor
levels."
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- Eating and exercising are inextricably intertwined, she
adds: "If you are willing to cut your food intake a bit more, you
may not have to exercise more."
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