Healthy Rx for Women's Hearts: Watch Your Weight and Stay Active
Staying both fit and trim are essential for women who want to avoid developing coronary heart disease (CHD), researchers report in Circulation: Journal of the American Heart Association.
"Our findings underscore the importance of both maintaining a healthy weight and regular physical activity in preventing coronary heart disease," said Frank B. Hu, M.D., Ph.D., senior author of the study and associate professor of nutrition and epidemiology at Harvard School of Public Health in Boston, Mass.
"Women who were inactive and obese had nearly three and a half times increased risk of having coronary heart disease when compared to active, lean women," Hu said.
Obesity and physical inactivity are individually recognized as major risk factors for heart disease. But some believe that maintaining a healthy weight while being sedentary is enough to prevent heart disease. Others believe being physically active despite being overweight will provide them adequate protection from heart disease.
"A high level of physical activity did not eliminate the risk of coronary heart disease associated with obesity, and leanness did not counteract the increased coronary heart disease risk associated with inactivity," Hu said.
Researchers examined the independent and joint associations of physical activity and obesity, employing body fat measurements, waist circumference and waist-to-hip ratios in 88,393 women ages 34 to 59 who participated in the Nurses' Health Study from 1980 to 2000.
Researchers said this is the largest study comparing the relative impact of "fatness and activity and risk of coronary heart disease in women" that uses repeated measures of physical activity levels.
The women were followed for 20 years. Every two years they completed a questionnaire on their medical history and lifestyle. Only 18 percent of the women reported that they were both lean and physically active.
In the study, women with a body mass index (BMI) from 18.5 to 24.9 kg/m2 were considered healthy weight and women with a BMI equal or greater than 30 kg/m2 were considered obese. (Body mass index is a mathematical score that shows body weight relative to height. It correlates highly with body fat in most people. Weight in kilograms is divided by height in meters squared [kg/m2]).
Women who exercised 3.5 hours per week or more were considered physically active while those who exercised less than an hour a week were considered sedentary.
Researchers documented 2,358 major CHD events - 889 were fatal and 1,469 were non-fatal heart attacks.
Compared to women who had healthy weights and were physically active:
- Women who were obese and sedentary were 3.44 times more likely to have coronary heart disease.
- Those who were active but obese were 2.48 times more likely to have coronary heart disease.
- Women who had a healthy weight but were sedentary were 1.48 times more likely to have coronary heart disease.
Researchers also noted that cigarette smoking combined with being obese and sedentary dramatically increased coronary heart disease risk - those women were nine times more likely to develop coronary heart disease than active, normal-weight nonsmokers.
The study group was primarily Caucasian, so the findings may not apply across ethnic groups.