If you sit for six hours a day or more, your risk of dying early jumps 19 percent, compared with people who sit fewer than three hours, an American Cancer Society study suggests.
And, the study authors added, sitting may kill you in 14 ways, including: cancer; heart disease; stroke; diabetes; kidney disease; suicide; chronic obstructive pulmonary disease (COPD); lung disease; liver disease; peptic ulcer and other digestive disease; Parkinson’s disease; Alzheimer’s disease; nervous disorders; and musculoskeletal disorders.
“The simple message is that we should be moving more,” said lead researcher Alpa Patel. She’s strategic director of the cancer society’s prevention study-3.
“The less sitting you do, the better it is for you,” she said. “Breaking up an hour of sitting with 2 minutes of standing or light activity can improve cholesterol, blood sugar and blood pressure.”
The study couldn’t prove cause and effect, but it’s clear that Americans are spending more time in their seats — watching TV, working and playing on computers and smartphones. With age people sit more, and people with chronic disease spend even more sedentary time, the researchers noted.
An Australian study estimated that 90 percent of non-working time was sedentary, and that more than half of it was spent watching TV or sitting at computers.
It’s not clear why prolonged sitting is unhealthy, Patel said. It’s possible that people who spend a lot of time on the couch also have other unhealthy behaviors, such as excess snacking, she suggested.
In addition, prolonged sitting has been linked to higher levels of triglycerides, blood sugar, blood pressure and insulin. Sitting has also been tied to inflammation caused by obesity.
These consequences might explain why sitting was linked with death from heart, liver and kidney disease, as well as cancer, diabetes and COPD, Patel said.
It’s less clear why death from suicide, Parkinson’s and Alzheimer’s, as well as nervous and musculoskeletal disorders, seems associated with sitting. For these, she said, it’s possible that the conditions themselves result in more sedentary time.