A Reminder To Proper Eating Habits
Getting regular exercise is obviously an important part of
staying healthy. But what about what we do with the rest of our
time? A new study suggests that the time we all spend sitting is
taking years off life expectancy in the U.S.
Scientists are just beginning to investigate how sitting affects
health, and early evidence has linked an excess of sitting time
to all kinds of chronic maladies, particularly heart disease,
diabetes and cancer. Now, a new analysis published in the
British Medical Journal suggests that the life expectancy of the
entire U.S. population could increase if Americans simply reduce
the time they reduce channel-surfing on the sofa.
Researchers looked at the results of five studies that explored
the effects on nearly 167,000 people of sitting and watching
television. Then they turned to national data collected by the
U.S. Centers for Disease Control and Prevention on how much time
Americans report sitting and watching TV.
Based on all this data, the researchers calculated that limiting
the time Americans spend sitting to three hours or fewer each
day would increase the life expectancy of the U.S. population by
2 years. Cutting down TV watching to fewer than two hours each
day would bump life expectancy up by another 1.4 years.
Exercise is a good thing, and getting the amount recommended by
groups like the CDC, the American Heart Association and the
National Cancer Institute -- 30 minutes of moderate to vigorous
exercise five times each week -- is a vital part of staying
healthy. But Peter Katzmarzyk, the study's lead author and a
professor at the Pennington Biomedical Research Center in Baton
Rouge, La., said it's becoming clearer that people need to do
"It is true that meeting the physical activity guidelines is one
of the best things you can do for your health. But on the other
hand, there are 23 and a half other hours of the day that we
can't ignore," he said.
Alpa Patel, an epidemiologist at the American Cancer Society,
agreed that the physical activity guidelines are important, but
she said they are based on research conducted over the last 60
"In that time, a lot of what we do in our daily lives has
changed," she said. "We've replaced much of what we used to do
with sedentary behavior, and we have to understand the
implications of that."
It's difficult for scientists to say that your recliner or your
television will kill you, and Katzmarzyk said the study doesn't
establish a direct cause-and-effect relationship between
sitting, TV watching and death. But the evidence suggesting an
association between shortened lives and sedentary activities,
like TV watching and driving, is piling up. For example, a 2010
study found that the mortality rates were 25 percent lower for
people reporting the most physical activity compared with those
reporting the least.
But what drives that association is unclear. Dr. Frank Hu, a
professor of nutrition and epidemiology at the Harvard School of
Public Health, said one possible explanation is that the health
effects come not so much from TV watching or driving themselves,
but the other things people do during those activities, such as
binging on unhealthy snacks or being stressed.
"Those behaviors are very detrimental to our health independent
of our physical activity levels," Hu said.
There also seems to be something about sitting itself that is
bad for one's health. Studies in both animals and humans have
found that sitting leads to changes in resting glucose levels
and blood pressure, and that lots of sitting bumps up levels of
certain biomarkers of cardiovascular disease and cancer.
"The take-home message is clear: we may not know exactly why
sitting is bad for you, but if you reduce the amount of time
spent sitting, there are real health benefits," Patel said.
Researchers say the overall message is to move beyond thinking
about physical activity as something you do once a day for half
an hour. That suggestion has enormous implications for how
people currently work, commute and spend their free time.
Katzmarzyk said since many people spend at least eight hours
each day sitting at a computer, the workplace is an ideal place
to start looking for ways to reform behavior. Patel said changes
don't have to be major -- people can get up to talk to
colleagues instead of emailing them, or spend a few minutes of
their lunch breaks taking a short walk.
And of course, a good place to start making changes is by
squeezing the recommended 30 minutes of exercise into every day.
"We have to get folks to understand that doing anything is
better than doing nothing," Patel said.