Instead,
losing excess weight — or not becoming overweight to begin
with — and exercising may do more to ward off death from heart
disease, say Jing Fang, M.D., and colleagues from the Albert Einstein
College of
Medicine in the Bronx, New York.
“The fact is that those who both exercised more and ate more nevertheless
had low cardiovascular mortality,” says Fang. Expending energy
through physical activity may be the key to cutting the risks of heart
disease
and living a longer, more healthful life, she says.
The study appears in the American Journal of Preventive
Medicine.
The researchers studied data from 9,790 participants in
the First National Health and Nutrition Examination Survey, a national
study from 1971 to
1975 that was funded by the U.S. government. Fang’s group compared
reports of physical activity, body mass index and dietary caloric intake
to deaths from heart disease through 1992.
They grouped participants by their initial reports of caloric intake (low,
middle, high), recreation exercise (least, moderate, most) and body mass
index (normal, overweight, obese). Body mass index is a measure of weight
in relation to height.
Overweight and obese participants, those who consumed fewer calories,
and those who exercised less were also likely to be older, black, have
a lower family income, less likely to have graduated high school, and more
likely to have higher blood pressure and cholesterol levels than those
who ate and exercised more.
During 17 years of follow-up, 1,531 participants died of heart disease.
After adjusting for BMI and physical activity, caloric intake was unrelated
to heart disease. Those who exercised more and ate more were both leaner
and had less than half the cardiovascular disease mortality than did those
who exercised less, ate less and were overweight.
“Subjects with the lowest caloric intake, least
physical activity, and who were overweight or obese had significantly
higher cardiovascular
mortality rates than those with high caloric intake, most physical activity,
and normal weight,” Fang says. The difference in mortality rates
was 55 percent.
Those who eat less won’t necessarily be thinner,
she says, and eating more does not have to translate into obesity. People
who were overweight
and exercised less at the start faced increased cardiovascular mortality,
even if they ate less.
“This suggests that heart disease outcome was not determined by
a single factor, but rather by a compound of behavioral, socioeconomic,
genetic and clinical characteristics,” she says.
A focus on increased energy expenditure rather than reduced caloric intake
may be the most practical outcome of this study, she says, and may offer
the most productive behavioral strategy by which to extend healthy life.
