University of Missouri-Columbia researchers Marc Hamilton and Theodore Zderic found evidence that sitting had negative effects on fat and cholesterol metabolism and that physical inactivity throughout the day stimulated disease-promoting processes.

Hamilton said that there is a misconception that actively exercising is the only way to make a healthy difference in an otherwise sedentary lifestyle but his studies found that standing and other non-exercise activities burn many calories in most adults even if they don't otherwise exercise.

"The enzymes in blood vessels of muscles responsible for 'fat burning' are shut off within hours of not standing," Hamilton said in a statement. "Standing and moving lightly will re-engage the enzymes, and it stands to reason that when people sit much of that time they are losing the opportunity for optimal metabolism throughout the day."

Common non-exercise physical activities include: household chores, shopping, fidgeting and standing while watching a ball game, watching TV or talking on the telephone.

The findings are published in Diabetes and are to be presented at the Second International Congress on Physical Activity and Public Health in the Netherlands.