You've probably heard that sitting all day is bad for you, but just how long do you need to spend standing up at your desk, or ambling on a treadmill at the office, to see health benefits?

A new study from Australia suggests that replacing 2 hours of sitting a day with standing may improve people's blood sugar and cholesterol levels; and that walking instead of sitting may have additional benefits for people's waistlines.

"These findings provide important preliminary evidence that strategies to increase the amount of time spent standing or walking rather than sitting may benefit the heart and metabolism," study researcher Genevieve Healy, of the University of Queensland's School of Public Health, said in a statement.

The study involved about 700 men and women ages 36 to 80 who wore an activity monitor 24 hours a day for a week. The monitors detected whether a participant was sitting, standing, stepping, lying down or sleeping.

On average, the participants spent 8.8 hours a day sitting, 4.9 hours a day standing and 2 hours a day stepping. They also got about 1.2 hours a day of moderate-to-vigorous physical activity, on average.

The researchers found that spending an extra 2 hours a day standing instead of sitting was linked with a 2 percent lower fasting blood sugar level, and an 11 percent lower level of triglycerides, or fats in the blood. [5 Tips for Sitting Less During Your Work Day]

In addition, replacing 2 hours of sitting a day with stepping was linked with an 11 percent lower body mass index (BMI) and a 3-inch (7.5 cm) smaller waist circumference.

The findings "provide some indication that cardio-metabolic benefits, particularly to glucose and lipid metabolism, may be achieved when reducing sitting through increases in standing," the researchers said. However, treadmill-desks, which allow people to walk instead of sit, "may be the approach most likely to achieve the greatest adiposity benefits," the researchers said.

The new study was conducted at a single point in time, so future studies that follow participants over time are needed to confirm the results.

In June, a panel of experts from the United Kingdom recommended that people with office jobs stand up for at least 2 hours a day at work.

The new study was published online July 30 in the European Heart Journal.

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