The findings, published in the Archives of Internal Medicine July 28, strongly encourage those who are overweight or obese to allot 60 minutes most days of the week to aerobic exercise.

The Physical Activity and Weight Management Research Center at the University of Pittsburgh studied 200 women between the ages of 21 and 45 for two years, giving them free treadmills and asking them to restrict their diet to 1,200–1,500 calories a day.

The women who lost at least 10 percent of their body weight “were exercising twice as long as health authorities typically recommend and expending more than twice as many calories through exercise as women who had no change in body weight,” Time magazine writes.

Maintenance was the strongest challenge for most of the women, many of whom temporarily relapsed about six months into the program. This pattern is typical, and most of the women bounced back, completing the two-year program with a net loss.

These more stringent guidelines are not entirely new. In 2007, members of the American College of Sports Medicine revised its standard exercise guidelines from 1995, which centered on 30 minutes of exercise three to five times a week. The new recommendations include weight training and jogging for those looking to maintain a healthy weight and prevent chronic conditions.

The emphasis is on consistency over rigor: make exercise a permanent part of your life, vary your routine, and share your goals with others, either through a program, Web site, or simply between friends and family members.