For those sedentary people who've adopted the I'm-fine-the-way-I-am philosophy regarding their weight, here's sobering news: If they hope to maintain that weight without dieting, they're going to have to exercise.
Besides helping people lose weight, exercise helps people maintain their weight. Without it, the average person gains a pound a year between ages 25 and 55. People who already tend to be heavy gain more.
The importance of exercise for weight maintenance was illustrated in a new study conducted at Duke University in Durham, N.C.
Researchers divided 120 sedentary participants, all overweight to mildly obese, into four groups. The control group did no exercise. A second group did the caloric equivalent of brisk walking 30 minutes a day, or 11 miles a week; a third group did the equivalent of jogging 20 minutes a day, or 11 miles a week; and the fourth did the equivalent of jogging 30 minutes a day, or 17 miles a week. (In fact, participants exercised on a combination of treadmills, cycle ergometers and elliptical trainers.) The men and women, who were between the ages of 40 and 65, were told not to change their eating habits during the eight-month study.
At the study's conclusion, 73% of participants in the two groups who logged the equivalent of 11 miles a week either maintained their weight or lost up to three pounds. Those in the most vigorous exercise group lost an average of six pounds each, or the equivalent of 10 pounds of fat, when adjusted for the lean body mass gained.
"But the most surprising finding," said Cris Slentz, exercise physiologist and lead researcher on the study, "was how fast the group who did nothing gained weight. We expect control groups to stay the same, but this group gained an average of 2.4 pounds in six months."
People who already are on the heavy side will continue on that trajectory unless they change what they do, Slentz said. "It's wrong to assume that if they do nothing they will hold their own."
Those in the study had a body mass index (BMI) of between 25 and 35. BMI calculates a person's overall size based on height and weight. Between 20 and 25 is normal. Between 25 and 30 is considered overweight, and anything over 30 is obese.
Tim Church, medical director of the Cooper Institute, a Dallas-based organization that studies fitness and health, applauded the study's emphasis on weight maintenance.
