Obese and overweight women need more exercise to sustain weight loss

The latest advice to overweight and obese women is that they need to exercise 55 minutes a day for five days per week, as well as limiting their calorie intake.

Researchers at the the University of Pittsburgh say in order to sustain a weight loss of 10 percent over two years, current recommendations of 30 minutes moderate physical activity most days of the week, may not be enough.

With many developed nations struggling to cope with increasing numbers of overweight and obese adults and children, the problem has become a public health concern.

The research team say long-term weight loss and prevention of weight regain programmes have been less than successful and a growing consensus suggests there is a need for more effective interventions.

In order to calculate the amount of exercise needed the researchers enrolled 201 overweight and obese women in a weight loss intervention programme between 1999 and 2003.

The women were told to eat between 1,200 and 1,500 calories per day and were assigned to one of four groups based on physical activity amount (burning 1,000 calories vs. 2,000 calories per week) and intensity (moderate vs. vigorous).

Over the two-year period the intervention team conducted meetings on strategies for modifying eating and exercise habits, as well as giving advice over the telephone.

According to lead researcher Dr. John M. Jakicic, after six months, women in all four groups had lost an average of 8 percent to 10 percent of their initial body weight but most were unable to sustain this weight loss.

After two years the women's weight was an average of 5 percent lower than their initial weight, with no difference between groups.

The researchers say almost 25% of those who did maintain a loss of 10 percent or more over two years reported performing more physical activity - an average of 1,835 calories per week, or 275 minutes per week over the baseline level of activity- compared to those who lost less weight.

They also had more telephone calls with the intervention team, engaged in more of the recommended eating behaviours and had a lower intake of dietary fat.

The researchers say this makes it clear how much physical activity is needed to achieve and sustain this magnitude of weight loss and also demonstrates the difficulty of sustaining this level of physical activity.

They suggest that the contact with the intervention staff and the ability to stick to the recommended diet were also important contributing factors to maintaining a significant weight loss.

The research is published in the July 28 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.