But new research shows that lazing around on the weekend is even worse than sitting all day at work. It’s so bad that it may undo the effects of your diligent desk breaks. Scientists from the University of South Carolina have found that being sedentary on weekends is surprisingly bad for you. They measured a group of 332 adults aged 20 to 35 with an activity meter and checked their bodyweight and body fat measurements. They found that a 20-minute reduction in sedentary time on Saturdays and Sundays added up to a loss of more than 2 pounds and 1.6 percent of body fat after a year. But the same association was not seen with sedentary time during the weekdays. The reason? The researchers said that people tend to eat more on weekends, which makes being sedentary worse.