or gainLOS ANGELES — Gloria Hale rose at 5:30 a.m. Tuesday, as usual, to swim laps before work. Active though she is, however, the 55-year-old Orange County, Calif., woman was a bit stunned to learn the latest advice from researchers regarding exercise — that women should work out 60 minutes a day, seven days a week, to maintain a normal weight over their lifetime.
“Most people are going to say, ‘No way. I don’t have time for that,’ ” said Hale, a trim 5-foot-5 and 138 pounds.
The 60-minute-a-day recommendation, released online Tuesday in the Journal of the American Medical Association, is aimed at women of normal weight who don’t want to diet but do want to avoid gaining weight over their lifetime. Most Americans gain about 1.5 pounds a year between ages 25 and 55.
But the issue of how much exercise is required to maintain a normal weight is far from settled. Other exercise experts say that an average of 35 minutes a day, seven days a week, probably is sufficient. But that’s still a lot of exercise.
“We wanted to see in regular folks — people not on any particular diet — what level of physical activity do you need to prevent weight gain over time,” said the lead author of the study, Dr. I-Min Lee, an epidemiologist at Brigham and Women’s Hospital in Boston, and an associate professor of medicine at Harvard University. “It’s a large amount of activity. If you’re not willing to do a high amount of activity, you need to curtail your calories a lot.”
The study was based on surveys of more than 34,000 U.S. women who were, on average, age 54 at the start of the study. They reported their physical activity and body weight, as well as health factors such as smoking and menopausal status, over 13 years. On average, the women gained 5.7 pounds during the study.
Only those women who were normal weight at the start of the study and engaged in moderate-intensity activity an average of 60 minutes per day, seven days a week, maintained a normal body weight, defined as a body mass index of less than 25.
“You can still do much for your health with a lower level of exercise,” Lee said. “But if you want to exercise for weight control, it’s 60 minutes a day.”
Moderate-intensity activities were defined in the study as walking or hiking, jogging, running, bicycling, aerobic exercise or dance, use of exercise machines, yoga, tennis, squash, racquetball, swimming. Housework and gardening were not included in the analysis.
It’s unclear what level of physical activity younger women need to maintain weight.
