CHICAGO — Rev up the treadmill: Sobering new research spells out just how much exercise women need to keep the flab off as they age — and it’s a lot.
At least an hour of moderate activity a day is needed for older women at a healthy weight who aren’t dieting. For those who are already overweight — and that’s most North American women — even more exercise is called for to avoid gaining weight without eating less, the study results suggest.
“We all have to work at it. If it were easy to be skinny, we would all be skinny,” said John Foreyt, a behavioural medicine expert who reviewed the study but wasn’t involved in the research.
Brisk walking, leisurely bicycling and golfing are all examples of moderate exercise. But don’t throw in the towel if you can’t do those things for at least an hour a day.
All measures of exercise are good for your health even if it won’t make you thin, the researchers said.
Their findings are based on 34,079 middle-aged women followed for about 13 years. Most were not on calorie-cutting diets. The women gained an average of up about 2.7 kg during the study.
Those who started out at a healthy weight, and who gained little or no weight during the study consistently got the equivalent of about an hour of moderate activity daily. Few women — only 13 per cent — were in this category.
Few already overweight women got that amount of exercise, and the results suggest it wasn’t enough to stop them from gaining weight.
The results echo what gymfuls of middle-aged American women see every time they step off the treadmill and onto the scale.
“Talk to any group of women and they all say the same thing,” said Janet Katzin, 61, a “slightly overweight” marketing director from Long Island who exercises for an hour twice a week. Thin as a younger adult, Katzin said the pounds started creeping up after she had her two children in the 1980s, despite exercising and watching what she eats. “It’s just extremely frustrating and discouraging.”
The study appears in Wednesday’s Journal of the American Medical Association. Only women were studied, so the researchers from Harvard’s Brigham and Women Hospital said it’s uncertain whether the results would apply to men.
The research “reinforces in a nice, clear way the idea of how difficult it is to maintain a healthy weight in our society,” said Foreyt of the Baylor College of Medicine in Texas.
The results bolster a 2002 Institute of Medicine report that emphasized the importance of balancing diet and exercise and recommended at least 60 minutes daily of moderate activity for adults and children. But it also indicates that guidelines urging about a half-hour of exercise five days a week won’t stop weight gain while getting older — unless you cut calories, said Dr. I-Min Lee, the study’s lead author.
The study underscores some inevitabilities about aging. Men and women often put on weight, partly because their metabolism slows down. But that probably has less to do with it than people’s natural tendency to become more sedentary, Lee said.
Hormonal changes in menopause also can make women prone to weight gain.
Women who don’t want to take on so much physical activity will need to cut back on calories to prevent more pounds. But Lee said they should do so in ways they can live with permanently, not with drastic diets that are doomed to fail.
Katzin, a size 14, said she does an hour workout twice a week — including weights, an elliptical machine and bike. “I know I should go more, but that’s all I can swing,” she said.
The researchers analyzed data on women who took part in a long-running federal study. Participants were 54 on average at the start and periodically reported how much they exercised and weighed. They also reported eating habits at the start, but not throughout, a limitation the authors acknowledged. Lee said the women’s eating habits were thought to be typical of American women who aren’t dieting.
This all doesn’t mean you have to starve yourself, but it does mean watching what you eat.
“You can eat a candy bar in two minutes. Most are at least 200 calories,” and to burn that off requires walking for about an hour, Lee said. Knowing that equation can help people make wise decisions about activity and food choices, she said.
On the Net: JAMA: http://jama.ama-assn.org