April 7, 2014 -- The studies just keep coming. Sitting our life away, it seems, may be very bad for our health and even our life expectancy.
Just since January, researchers have reported that sitting for long hours is linked to:
- Worse mental health
- A higher risk of death from heart disease and other causes
- A higher risk of being disabled
The new studies add even more weight to earlier research suggesting that too much sitting is bad -- even if you get regular exercise.
Experts say they still don't know for sure which comes first. Does too much sitting trigger poor health, or is it the other way around?
They also say we may need to think about sitting and exercise as two separate behaviors, each contributing on its own to our health. So while that 1-hour jog is great for you, it may not undo the 8 hours sitting at your desk.
WebMD asked three experts to weigh in on what we know about sitting and how we can reduce our sitting time.
What health problems have too much sitting been linked to?
''It has been linked to cardiovascular events like heart attack, heart disease death, overall death, and death from cancer," says Andrea LaCroix, PhD, director of the Women's Health Center of Excellence at the University of California, San Diego.
In her recent study, she found that older women who reported the most sitting time were more likely to die during the 12-year follow up. Those sitting more than 11 hours daily were at the highest risk, she reported in the American Journal of Preventive Medicine.
The dangers of excess sitting have been discussed for decades, but research has picked up steam in the last 5 years, says Jacqueline Kerr, PhD, associate professor of family and preventive medicine at UC San Diego. She studies how to help people sit less.
Why is sitting too much linked with health problems?
Scientists can't explain it. And they emphasize that a link doesn't prove that too much sitting causes these diseases.
One possibility: Sitting for a long time causes muscles to burn less fat and blood to flow more sluggishly. Both can increase the risk of heart disease, high blood pressure, and other problems.
In some cases, it's still unclear which way the link goes, says Barry Braun, PhD, director of the Energy Metabolism Laboratory at the University of Massachusetts in Amherst. "People who sit the most are more likely to be obese,'' he says. "Are people obese because they sit too much, or do they sit too much because they are obese?"
How does sitting affect appetite?
You might think that sitting would make you less hungry. Braun's research has found it is not true.
His team assigned people to sit a lot one day and to stand a lot on another day. Each time, the researchers studied how it affected their appetite. ''Going from active to sitting doesn't lower your appetite or your energy intake," he says. Prolonged sitting, he says, may trigger us to eat more than we should, leading to weight gain.
Why doesn't physical activity seem to compensate?
Researchers are trying to figure out if sitting and exercise ''are two different components driving health," LaCroix says. "I am not at all certain this is true, but we are trying to figure it out."
Even though the idea is evolving, Kerr says it may help people to think about being active and sitting as two separate ways to improve or harm your health. "Does exercise compensate for a bad night's sleep?" she asks. "So why should exercise compensate for the fact that you sit all day?"
What's the take-home message from the research?
''Don't demonize sitting," LaCroix says. The message, she says, is to reduce sitting time by breaking it up. Although experts aren't sure how often you need to get up, they suggest getting up about every 30 minutes if possible.
Kerr tells people to value some sitting time. "Sitting while you are socially engaged might be something that's very good for you," she says. Likewise, sitting for a few minutes to decompress after a stressful day could be good for you.
Think big picture, Kerr and LaCroix say, and stand when you can.
How can the average person reduce sitting time?
- Use a standing desk at work. More workplaces are warming to the idea, she says.
- Give yourself reminders to sit less. At home, consider a TV commercial your signal to get out of your chair briefly. At work, use a smaller coffee cup or glass so your trips for refills will be more frequent.
- Change social norms. Kerr suggests: At a meeting, you might explain, "I am going to take a standing break."
Once people sit less, Kerr finds, they often are open to the idea of moving more and to being more active.