1. High heels can cause sprained ankles and feet as well as broken bones. Injuries involving high-heeled footwear doubled in the U.S. between 2002 and 2012, researchers learned, during which time American women suffered more than 123,355 mishaps severe enough to warrant a trip to the emergency room. Those fashionable pumps and strappy sandals can affect gait, balance, and range of foot motion, warns lead investigator Gerald McGwin, and it's important to "understand the risks and the potential harm that precarious activities in high-heeled shoes can cause."

2. Belly fat is a serious health concern, even if you're thin. Men and women with excess weight around the middle are significantly more likely to die from heart disease than adults whose fat is more evenly distributed, a Mayo Clinic study revealed, no matter where they tip the scales. Even in people with a "normal" body mass index — a weight-height ratio — belly blubber is linked to a buildup of deeper visceral fat that wraps around internal organs, increasing the risk for heart attack, stroke, and type 2 diabetes. "We need to talk about waist loss," says cardiologist Paul Poirier, "not weight loss."

3. Sitting may be worse for us than smoking. A study revealed that remaining sedentary for extended periods can dramatically increase the risk for chronic health issues, including heart disease, diabetes, and depression. Not only that, but the negative effects of prolonged sitting aren't offset by intense exercise before or after work. People with desk jobs should be on their feet for at least two hours daily, either by taking occasional strolls or using a standing desk. "We are creatures of habit," says co-author Gavin Bradley, "and we have come to the wrong conclusion, that sitting is the optimum way of conducting office work."

4. Shift work can be unhealthy, increasing the risk of heart disease, obesity, and metabolic disorders. Researchers in Finland tracked airline employees and found that people who worked nights or irregular hours slept less than peers who were scheduled for the regular business day. Beyond that, "it seems that shift work itself strongly affects workers' eating habits," says study leader Katri Hemio, noting they ate fewer vegetables and consumed more fat. One way to address the problem, experts say, is to stock workplace vending machines with healthier foods and provide refrigerators, so employees can bring healthier meals from home.

5. Zip lines are dangerous. As more and more people soar above ground while suspended from a wire, an alarming number are getting hurt. A study of a Consumer Product Safety Commission database revealed that the injury rate from zip lines surged by more than 50 percent between 2009 and 2012. Most accidents occurred at commercial courses, but roughly 30 percent were on amateur "backyard" setups. Young children accounted for almost half the injuries, which usually involved broken bones sustained during falls or collisions. The rate and severity of zip line injuries, says researcher Tracy Mehan, suggests "this activity is much more like an adventure sport."

6. Dietary supplements can land you in the hospital. They're responsible for at least 23,000 emergency room trips and 2,100 hospital admissions in the U.S. every year, a study found, suggesting these loosely regulated "natural" substances aren't always safe. After analyzing 10 years of data, researchers established that 65 percent of these ER visits were prompted by chest pain, palpitations, and dizziness. The worst offenders were herbal formulas promising to accelerate weight loss, boost energy, or enhance sex drive, all of which are laced with stimulants. "Many Americans take dietary supplements in an effort to stay healthy," says study author Andrew Geller of the Centers for Disease Control and Prevention, "but these products can cause harm."

7. Loneliness increases the risk of death by up to 14 percent, a University of Chicago study found. The stressful pangs of unwanted solitude trigger the "flight or fight" response, causing inflammation and cellular changes that disrupt the production of white blood cells that protect the body from illness. Social isolation does improve the body's ability to fight harmful bacteria, but it also makes people more susceptible to viral infections. "The lonelier one is and the longer one is lonely," author John Cacioppo says, "the greater the negative effects."