Tuesday, April 29, 2008

Too Fat? First, Get off the Couch

There's been a lot of debate over the past several years about whether you can be both fit and fat. That is, can you be overweight but as healthy as a lean person if you exercise regularly? A study released today in the Archives of Internal Medicine suggests that at least as far as heart disease in women goes, body weight and exercise are both important variables. The discussion is complicated by the fact that the body mass index, the number researchers typically use to gauge overweight and obesity, is not always a perfect measure of body fatness. On one hand, because it simply relates weight to height, it may put musclebound but lean athletes into the "overweight" category. (Here's a study looking at its use in college athletes and nonathletes.) And as I wrote earlier this month, a low BMI may give some thin people a false sense of security, even though their percentage of body fat is high. Studies looking at the relationship between health and exercise and body weight are often confusing. One, published in December in the Journal of the American Medical Association, found that among people 60 and older, fitness was the better predictor of longevity than BMI. And the study released today says that yes, exercise absolutely makes a difference in the risk of heart disease among the overweight and obese. But so does weight. Compared with women of normal weight (a BMI less than 25) who were active (or burned off at least 1,000 calories a week), inactive overweight women had an 88 percent higher chance of developing heart disease; active overweight women had a 54 percent higher risk. In women who were obese, the active group had an 87 percent higher chance of getting the disease, while the inactive obese women were at highest risk: Their odds of getting heart disease were more than 2½ times as high as those for the lean active women. The lean women, even the inactive ones, still had far lower odds of later developing heart disease than the overweight women, including those who were exercising. "The physical activity did make a significant difference and reduced the risk of heart disease. But according to our study, to fully reverse the risk of heart disease from being overweight or obese, you'd also have to lose weight," says Amy Weinstein, an instructor of medicine at Harvard Medical School and an author of the study... US News

Exercise-heart study casts doubt on 'fit but fat' theory

New research challenges the notion that you can be fat and fit, finding that being active can lower but not eliminate heart risks faced by heavy women. "It doesn't take away the risk entirely. Weight still matters," said Dr. Martha Gulati, a heart specialist at Northwestern Memorial Hospital. Previous research has gone back and forth on whether exercise or weight has a greater influence on heart disease risks. The new study involving nearly 39,000 women helps sort out the combined effects of physical activity and body mass on women's chances of developing heart disease, said Gulati, who wasn't involved in the research. The study by Harvard-affiliated researchers appears in Monday's Archives of Internal Medicine. Participants were women aged 54 on average who filled out a questionnaire at the study's start detailing their height, weight and amount of weekly physical activity in the past year, including walking, jogging, bicycling and swimming. They were then tracked for about 11 years. Overall 948 women developed heart disease. Women were considered active if they followed government-recommended guidelines and got at least 30 minutes of moderate activity most days of the week, including brisk walking or jogging. Women who got less exercise than that were considered inactive. Weight was evaluated by body mass index: A BMI between 25 and 29 is considered overweight, while obese is 30 and higher... AP