Thursday marks the fifth annual "National Fitness Day". The anniversary of the start of the 2008 Olympic Games in Beijing, the day reminds people to take more exercise to help them stay healthy, and many cities across the nation held activities like opening stadiums for free or organizing sport competitions.

It seems that many people need such a reminder.

On Monday, the General Administration of Sport released the results of a national survey of more than 43,000 adults aged between 20 and 69. The survey found their average body weight has increased by 1.12 kilograms compared with the average weight in 2010, and the average body weight of the group aged between 20 and 39 gained 1.92 kg, the highest among all the respondents. The same age group is also the least active, 51 percent said they did not do any regular exercise, despite a 4.5 percent increase in the total number of people doing regular exercise.