By Tanner Garrity Over the last few years, as researchers have publicized the perils of a sedentary, screen-heavy lifestyle, the catchphrase “sitting is the new smoking” has picked up some steam. It’s a tad bombastic — never underestimate how bad smoking is for your body and brain — but constant sitting does disrupt the body’s ability to break down body fat, while slowing metabolism and elevating blood pressure. In identifying a “new smoking,” though, we might have to look elsewhere: to loneliness. A well-known meta-analysis linked loneliness with increased risk of heart disease and depression…