Obesity Raises Women’s Heart Risk, Study Affirms

Middle-age women who are even mildly overweight have a significantly greater risk of coronary heart disease than their leaner counterparts, according to a new study that suggests obesity is even more dangerous than previously thought.

The study of 115,886 U.S. women found that those who were slightly overweight were nearly twice as likely as lean women to experience heart attacks and angina. Those who were 30% overweight or more were more than three times as likely to develop heart disease.

The new findings are expected to help settle a long-running controversy over the relationship between obesity and heart disease in women. Although fat is known to contribute to heart disease in men, past studies of women have been contradictory.

The study’s implications are especially ominous in the United States, where one-quarter of all women between 35 and 64 are at least 30% overweight, and where heart disease is already the nation’s top killer of women as well as men.

“The public health impact of obesity has not been fully appreciated,” said Dr. JoAnn Manson, a co-author of the study. “. . . It’s a challenge to the health profession to develop effective strategies in helping people to avoid weight gain with middle age.”

The study by researchers at Brigham and Women’s Hospital in Boston and Harvard Medical School was published today in the New England Journal of Medicine. It followed nurses between the ages of 30 and 63 in 11 states over eight years.

The researchers put the women in five categories ranging from lean to seriously overweight, as defined by actuarial tables. Lean women weighed on average 119 pounds; average women ranged from 137 to 148 pounds; the heaviest women weighed an average of 193 pounds.

The results include the following:

Women who were “mildly to moderately overweight” (from 149 to 171 pounds for an average height of 5 feet, 4 1/2 inches) were 80% more likely than lean women to develop coronary heart disease during the study period.

Women who were at least 30% overweight were 3.3 times as likely as lean women to develop heart disease.

Even women of average weight carried a 30% higher risk of heart attack than their leaner counterparts.

A weight gain of more than 20 pounds since age 18 doubled the risk of heart attack.

Overweight women who smoked were five times more likely than overweight nonsmokers to experience a heart attack.

“The primary message from this study is one of the importance of prevention,” said Manson, a physician and researcher at Brigham and Women’s Hospital. “That’s directed mostly to young women, to encourage them not to gain the weight during adulthood that so commonly occurs in the United States.”

Obesity leads to heart disease primarily by increasing one’s risk of high blood pressure, diabetes and unusually high levels of fat in the blood. Those and other risk factors for heart disease can be caused or exacerbated by being overweight.

Although physicians often recommend weight loss to treat hypertension, diabetes and high cholesterol levels, it was impossible in the study to say whether weight loss reduced heart-disease risk because too few women lost weight during the study period.

Manson’s study is not the first to conclude that obesity is associated with increased risk of heart disease. But the relationship in women has been controversial; some researchers have found an association while others have not.

A possible explanation for those discrepancies lies in the methods used by different researchers. For example, some researchers did not take into account the effects of smoking, which is more common in thin women but greatly increases one’s risk of heart disease.

“This will tend to inflate the risks associated with leanness and lead to an underestimation of the risks of obesity,” said Manson, whose study was more comprehensive than many others and who controlled for the effects of smoking.

Some researchers had also suggested that obesity might be less risky in women than in men because women’s fat tends to accumulate around the hips and legs. Obesity in the trunk, as in men, appears to carry a greater heart-disease risk than obesity elsewhere in the body.

Experts in the field said Wednesday that the new findings should eradicate the notion that some degree of obesity is safe, and should prompt physicians and public health officials to devote more attention to encouraging weight loss.

Dr. William P. Castelli, director of the Framingham Heart Study, a long-running, federally funded project based in Framingham, Mass., said campaigns to control blood pressure and cholesterol should begin by getting people to lose weight.

“A lot of them, by doing that, will straighten out their risk factors (for heart disease),” Castelli said. “There are few things you can do that will change so many risk factors at once (that are as effective as) losing weight.”

“It certainly makes me stop and think,” said Dr. Michael Crawford, chief of cardiology at the University of New Mexico School of Medicine and chairman of the American Heart Assn.’s clinical council.

“Because I’ve been fairly complacent about obesity in women, as a cardiologist, up until now,” Crawford said. “This is going to give me pause.”