Overweight women need more exercise to maintain weight loss

A study published in the Archives of Internal Medicine found that overweight and obese women need to do more than just limit calories in order to sustain a 10% weight loss over two years: they also need to exercise 55 minutes per day, five days per week.

The study, conducted by John Jakicic and colleagues from the University of Pittsburg, calculated the amount of exercise needed by studying 201 overweight and obese women who enrolled in a weight loss intervention between 1999 and 2003. After all women were instructed to eat 1 200 to 1 500 calories per day, the researchers divided them into one of four physical activity groups: one group burned 1 000 calories per week, one burned 2 000 calories per week, one carried out moderate exercise, and the final group carried out vigorous exercise. The women also attended group meetings to discuss strategies for changing eating and exercise habits and received telephone calls from the intervention team over the two years of the study.

Results at the end of six months showed an average weight loss of 8 to 10% of initial body weight for women in all four groups. Maintenance of this weight loss, however, proved more difficult. At the end of two years, the average women's weight was about 5% lower than initial body weight, and there was no significant difference among the four groups.

Of all the women, 24.6% managed to sustain a weight loss of at least 10% o percent of initial body weight over two years. These women were more physically active than those who lost less weight, burning an average of 1 835 calories per week or having exercised 275 minutes per week more than baseline activity levels. In addition, this group of women completed more telephone calls with the intervention team, practiced healthier eating behaviors designed for weight control, and ingested a smaller amount of dietary fat.