So you've read that a sedentary lifestyle may be more dangerous than smoking? Hope you didn't buy a new stand-up desk, because the research in question failed to prove a link between inactivity and early death, writes The Numbers Guy at the Wall Street Journal: "It could be that people who spend more time sitting are less healthy to begin with, or that those who sit less are using that time in healthier ways such as exercising."
Dr. Peter Katzmarzyk's analysis of sedentary health risks was a so-called observational study—which amasses evidence toward cause and effect but doesn't prove it. Such studies "often are the closest scientists get to directly connecting behavior with lifespan," concedes The Numbers Guy. What's more, controlled studies that focus on the dangers of sedentary lifestyle would be both expensive and "ethically dubious." So while Katzmarzyk's work does make sense, that "doesn't mean the act of sitting itself is deadly."