July 28, 2008 -- How much do you have to work out in order to lose weight and keep it off? The answer is hotly debated among people who study weight loss.
A new study says that obese and overweight women need to cut calories and exercise 275 minutes a week more than their baseline physical activity -- or at least 55 minutes a day, five days a week to lose weight and keep it off.
The research was led by John M. Jakicic, PhD, of the University of Pittsburgh, and colleagues.
They tracked 201 overweight and obese women over a two-year period; 170 women completed the study.
At the start, all of the participants were sedentary. They were randomly assigned to one of four groups based on how much and how intensely they exercised and how many calories they burned.
The participants were told to eat or drink no more than 1,200 to 1,500 calories a day. Researchers tracked them by talking to them on the phone and having face-to-face talks.
Participants were encouraged to spread the exercise out over five days during a week, done in at least 10-minute chunks. The women were given treadmills to use at home and taught to monitor their own heart rates.
At the end of the two-year study, women who had lost 10% or more of their initial body weight reported that they had done more physical activity compared with those who did not lose as much weight.
After six months, women in all four groups had lost an average of 8% to 10% of their initial body weight. But the hard part was keeping that weight off. Most of them regained the weight.
Nearly 25% of the participants managed to keep 10% or more of their original body weight off over the two years.
Those women exercised about 275 minutes a week more over their baseline activity levels.
They also got the most support, completing the most telephone calls from researchers, and said they participated in more eating behaviors recommended for weight control than those who gained the weight back.
Those who lost and kept off the weight also increased their leisure time physical activity, doing things like taking the stairs and moving about more at home and work.
A couple of limitations the study authors note are that diet alone was not included as one of the options and that the participants themselves reported what physical activity they did and how well they did it.
The study authors conclude that a relatively high level of physical activity is needed to lose weight and keep it off.
These results are likely to add fuel to the debate over how much is needed to lose pounds and keep them from creeping back.
General recommendations are for 30 minutes a day, or 150 minutes a week, of moderately intense activity most days of the week. But the debate rages on over a magic formula for sustaining weight loss.
The findings are published in the July 28 issue of Archives of Internal Medicine.