Healthiest formula may be slim and active

Obese women seem able to avoid heart disease by exercising, but they're more likely to develop diabetes if they don't lose weight. Slim women, on the other hand, face probable heart troubles if they don't exercise, but potential diabetes is less likely for them.

What to do? Leaders of the two studies that yielded these findings said that, in the end, women need to be both slim and fit to be healthy.

"There is a very strong interaction between obesity and level of physical activity," Dr. Carl J. Pepine, director of cardiovascular medicine at the University of Florida College of Medicine and the leader of one study, told HealthDay .

But that study also showed that "a lean woman who is not fit has a high risk of cardiovascular disease," Pepine said.

The 906 women in the study had doctors who suspected heart disease and had them undergo coronary angiography, which tests for blockage of the heart artery. Their physical activity, body mass index and abdominal obesity also were measured.

Most of the women were fat and inactive: 76 percent were overweight, and 70 percent had low functional exercise capacity. Over the next four years, 337 of them had a first-time heart attack or other serious heart problem.

Lack of physical activity was a strong predictor for this problem, but there was no significant association between obesity measurements and cardiovascular risk, the study found. That means that women who have trouble losing weight can help themselves by exercising, Pepine said.

Women shouldn't think that they have to be running marathons to gain health benefits.

"We're not necessarily talking about high levels of fitness," Pepine said. The finding supports the American Heart Association recommendation of at least 30 minutes of moderate physical activity most days of the week, he said.

The other report was based on nearly 38,000 participants in the ongoing Women's Health Study. It found that both obesity -- a body mass index of 30 or higher ( 174 pounds for a 5-foot-4-inch woman) -- and physical inactivity boosted the risk for diabetes. But the risk of diabetes because of obesity was more than nine times greater for an obese woman than for a woman of normal weight.

By contrast, the risk of diabetes was no more than 18 percent higher in the least active women, compared with the most active.

"This study showed that obesity has far and away a more important effect on developing adult-onset diabetes," Dr. J. Michael Gaziano, an associate professor of medicine at Brigham and Women's Hospital in Boston and a leader of the study, told HealthDay .

"I would not want to underemphasize the importance of physical activity in maintaining proper body weight," Gaziano said. "But being physically fit is not enough to have an impact on the risk of diabetes. You need to lose weight as well."

The message is that diabetes is not inevitable an obese person, he said.