Office workers could lose almost half a stone a year simply by standing up at their desks, new research suggests.
The international study of more than 1,000 men and women found that standing instead of sitting for six hours a day burned an extra 54 calories daily - resulting in significant weight loss.
The research, published in the European Journal of Preventive Cardiology, found that standing burned almost twice as many calories in men compared with women, compared with their higher muscle mass.
The study, which examined data from 1,184 people taking part in 46 previous studies, found the average difference in energy expenditure between sitting and standing was 0.15 calories a minute.
It means those who spent six hours of the day standing rather than sitting could expect to lose almost six pounds in a year if they did not change their diet.
Researchers said many office workers could achieve significant weight loss if they spent regular periods standing at their desks, especially if it encouraged them to move about more.
Senior author Dr Francisco Lopez-Jimenez, chairman of preventive cardiology at Mayo Clinic, in Minnesota, said: "Standing for long periods of time for many adults may seem unmanageable, especially those who have desk jobs, but, for the person who sits for 12 hours a day, cutting sitting time to half would give great benefits."
Researchers found the effects were most pronounced among men, which they said was likely to reflect the fact those with greater muscle mass burn calories more quickly.
Prof Lopez-Jimenez said the results might even be an underestimate, and said standing could also boost overall health.
"Standing not only burns more calories, the additional muscle activity is linked to lower rates of heart attacks, strokes, and diabetes, so the benefits of standing could go beyond weight control.
"Our results might be an underestimate because when people stand they tend to make spontaneous movements like shifting weight or swaying from one foot to another, taking small steps forward and back. People may even be more likely to walk to the filing cabinet or trash bin.
"It's important to avoid sitting for hours at a time. Standing is a very good first step to avoid this mindset of sitting interminably without moving.
"Who knows, it may also prompt some people to do a little more and take up some mild physical activity, which would be even more beneficial."
When people are standing, more muscles are tensed and stretched to fight gravity and bear weight.
Researchers stressed that the weight loss from extra time standing would only be achieved if the extra calories burned were not counteracted by an increase in food intake.