For those of us who spend the majority of our working day in a desk chair, the news from health researchers the last few years has been decidedly bad.

The central message of the researchers’ studies is this: the more time you spend sitting each day, the greater your chance of dying within the following three to 15 years (depending on which study you consult).  In the latest study to support this claim, the sitting-equals-death threshold was 11 or more hours a day. For the age-group studied (45 years and older), those who sat 11 or more hours a day had a 40% greater chance of dying within three years, as compared to people who sat four or less hours a day.

To put this in context, let’s say that you are an otherwise healthy person without a genetic history of heart disease or cancer, and your baseline chance of death within three years, per standard insurance statistics, is around 10%. According to this study, sitting for 11 or more hours a day over time increases that risk to 50%. That doesn’t mean your likelihood of dying is 50%, but that your risk of dying is significantly greater than that of someone who doesn’t sit for hours on end.

The frightening part about these studies is that they’ve cut a gaping hole in the safety net many of us thought we’d created to mitigate the risk — regular exercise. The research is quite clear that even among those who exercise, the elevated chance of death remains high.  Regular exercise helps (defined in the latest study as 5 or more hours a week), but it doesn’t entirely balance the scale.

The reason sitting is dangerous involves a combination of factors.  The first, and most obvious, is that the more we sit the less calories we burn and more of what we consume is stored as fat.  Over time, as we’re all well aware, carrying around excess fat predisposes our bodies to a range of health problems including diabetes and heart disease.

The less obvious reasons are more immediate, including a rapid drop in a circulating blood enzyme called lipase that is responsible for breaking down fat.  One study puts this drop at 90% – a virtual shut down.  In addition, electrical activity in our leg muscles radically decreases the longer we sit, and that means that our metabolic rate slows to a crawl, to about one calorie per minute.  And one of the most dangerous outcomes of sitting for extended periods is that our bodies become less sensitive to the insulin our pancreas is busy producing (24% less sensitive according to one study), and that skyrockets the risk of developing Type 2 diabetes.