According to a study published in the journal Diabetologia in July 2012, those with excessive sitting habits—by some definitions a mere four hours a day—double their risk of developing diabetes and cardiovascular disease, increase their risk of dying from heart disease by 90 percent, and increase their risk of premature death from any cause by 49 percent. By comparison, smoking triples a middle-aged woman’s chance of dying from heart disease.

And while the numbers were slightly lower, a 2010 study, published in the American Journal of Epidemiology, of people who sat more than six hours and were minimally active in all aspects of leisure time showed the news is worse for women: Females who sat more than six hours daily showed a 34 percent increased risk of dying prematurely, while men had a 17 percent increase. 

Why is sitting unhealthy? Dr. Emma Wilmot, research fellow in the Diabetes Research Group at the University of Leicester and lead researcher for the Diabetologia study, suspects sitting causes changes in postural muscles and in how fats and glucose are metabolized, changes which come with adverse health effects. 

Both studies also show hitting the treadmill isn’t enough to counteract hours of sitting. To reduce risks one must actually sit less. Instead of e-mailing, walk to coworkers’ offices; stand up during phone calls; use a standing desk; and stretch while watching TV. 

Dr. Alpa Patel, epidemiologist at the American Cancer Society, and the 2010 study’s lead researcher, puts it this way: “I think (for me) the message has been that small steps can make a big difference in your health.”