When I first heard that sitting too much was associated with chronic disease, I was extremely skeptical. Of course it is, I thought... people who sit more exercise less, they lose cardiovascular fitness, and they burn fewer calories throughout the day, setting themselves up to gain weight. It's not that sitting too much directly promotes disease, I thought; it must be all that goes along with it. It's the lack of exercise and the weight gain that's the real problem.
Welp, I was wrong (1). Turns out, we now know of specific molecular processes that take place when we sit, and they're distinct from intentional exercise. In fact, even if you get the "recommended" amount exercise, 30 minutes a day, you can completely undo those metabolic benefits by spending the rest of your day sedentary in a chair. Sitting continuously sets off a series of unwanted cellular mechanisms that immediately reduce your HDL and increase your triglycerides, two common risk factors for cardiovascular disease. Over the long term, we put ourselves at high risk for chronic disease, and that includes heart disease, high blood pressure, diabetes, and obesity.