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No standing pat

Happy with your weight? Then start exercising, because as time passes, it may take more effort just to maintain it.

January 19, 2004|Marnell Jameson | Special to The Times

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.

"Losing weight and keeping it off is much harder than maintaining weight," he said. "When the body gains weight, it resets its baseline and seeks to maintain that, which is why few people will ever see their prom weight again. It's much easier to work on not gaining. If people just hold their weight and gain fitness, they will see tremendous health benefits."

Slentz said he and his group did the study because, though most people realize exercise promotes weight loss and the maintenance of weight loss, the amount of activity needed to prevent weight gain was unknown.

"In the end, it all gets back to caloric balance," he said. Those on track to gain a pound a year are taking in an average of 10 calories a day too much. The overweight subjects in his study were on track to gain five pounds a year. That averages out to 48 calories a day too many, or half a slice of bread. That's not much, and is easily offset by a brisk daily walk.

Although weight loss varies among individuals, Slentz said, the study indicated that if people walked just one mile a day, or seven miles a week, they probably could maintain. "If that's not enough, you need to up the dose," he said, "Exercise is like medicine that way. You adjust till you get the dose right." Only in this case, more could indeed be better and result in greater weight loss.

Just 30 minutes a day most days of the week are all you need to maintain weight and fitness, Church said. "Some groups have come out saying you need to work out an hour a day," he added. "Not only is that unrealistic, the science says it's unnecessary."

Finally, those starting on a fitness program should not be discouraged by slow or what they perceive as no results.

"I see people who have been steadily gaining two pounds a year," said Slentz. "They start walking eight to 10 miles a week and complain that after nine months they haven't lost a pound. That needs to be interpreted in a different light: They didn't gain any weight. That is a real success."

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