What are the risks of sitting too much?
Research has linked sitting for long periods of time with a number of health concerns, including obesity and metabolic syndrome – a cluster of conditions that includes increased blood pressure, high blood sugar, excess body fat around the waist and abnormal cholesterol levels. Too much sitting also seems to increase the risk of death from cardiovascular disease and cancer.
One study compared adults who spent less than two hours a day in front of the TV or other screen-based entertainment with those who logged more than four hours a day of recreational screen time. Those with greater screen time had:
- A nearly 50 percent increased risk of death from any cause
- About a 125 percent increased risk of events associated with cardiovascular disease, such as chest pain (angina) or heart attack
The increased risk was separate from other traditional risk factors for cardiovascular disease, such as smoking or high blood pressure.
Any extended sitting – such as behind a desk at work or behind the wheel – can be harmful. What’s more, spending a few hours a week at the gym or otherwise engaged in moderate or vigorous activity doesn’t seem to significantly offset the risk.
Sitting for long periods has not only linked to obesity, diabetes and heart disease – and now there’s new evidence that it may also increase the risk of liver disease, according to a new study from South Korea.
In the study, researchers found that people who sat for 10 or more hours daily had a 9 percent greater risk of developing a condition called nonalcoholic fatty liver disease (NAFLD) than those who spent less than five hours a day sitting.
Physical activity also played a role in people’s risk of NAFLD: Those who were physically active were 20 percent less likely to develop the disease compared with those who were inactive, according to the study published on September 15 2017 in the Journal of Hepatology. [How Many Calories Am I Burning? (Infographic)]
“The amount of time spent doing sedentary activity such as sitting at a computer or watching TV has increased dramatically in recent years,” Dr. Seungho Ryu, professor of occupational and environmental medicine at Kangbuk Samsung Hospital in South Korea and lead author of the study said. Now, “more than half of the average person’s waking day involves sedentary activities,” he said.
In the study, the researchers looked at more than 139,000 Korean men and women who reported their levels of physical activity and sitting time. NAFLD was confirmed using ultrasounds.
The average age of the participants was 39.9 years, according to the study. Because the people in the study were generally healthy – young and middle-age men and women – it’s unlikely that other health problems can explain the link between sitting time and physical activity with NAFLD, Ryu said.
The study suggests that regular physical activity, even at a high intensity, does not fully protect against the risks associated with prolonged sitting, he said. If the results of the study are confirmed, it will be important to encourage people to both increase their physical activity and reduce their sitting time to reduce the risk of developing NAFLD, he said.
Even doing light activity instead of sitting may help reduce the risk of NAFLD, Ryu added.
“Our body is designed to move, and it is not surprising that sedentary behavior, characterized by low muscle activity, has a direct impact on physiology,” Michael Trenell, a professor of metabolism and lifestyle medicine at Newcastle University in England, wrote in an editorial that accompanied the study in the journal.
Sedentary behavior can increase the risk of insulin resistance and can lower cardiovascular function, he wrote. In people with insulin resistance, body cells lose their ability to respond to insulin by taking in sugar from the blood, leading to high blood sugar levels, and, sometimes, Type 2 diabetes.
“What remains less certain is the effect of sedentary behavior on the liver,” he said.
Currently, there is a lack of drugs approved for treating people with NAFLD, so lifestyle changes are the primary means of treating the disease, Trenell wrote. In general, 150 minutes of moderate exercise per week or 10,000 steps per day are considered good rules of thumb for physical activity, he wrote.
“However, the current literature cannot inform us how much sitting is too much,” Trenell wrote. “We just know that it is better to sit less than to sit more.”
About 19 percent of Americans have NAFLD, according to a 2013 study in the American Journal of Epidemiology. The condition can lead to swelling and scarring of the liver, according to the American Liver Foundation.
The solution seems to be less sitting and more moving overall. You might start by simply standing rather than sitting whenever you have the chance or think about ways to walk while you work. For example:
- Stand while talking on the phone or eating lunch.
- If you work at a desk for long periods of time, try a standing desk – or improvise with a high table or counter.
- Walk laps with your colleagues rather than gathering in a conference room for meetings.
- Position your work surface above a treadmill – with a computer screen and keyboard on a stand or a specialized treadmill-ready vertical desk – so that you can be in motion throughout the day.
The impact of movement – even leisurely movement – can be profound. For starters, you’ll burn more calories. This might lead to weight loss and increased energy. Even better, the muscle activity needed for standing and other movement seems to trigger important processes related to the breakdown of fats and sugars within the body. When you sit, these processes stall – and your health risks increase. When you’re standing or actively moving, you kick the processes back into action.
Credit: James A. Levine, M.D., Ph. D./Sarah G. Miller
References: Mayo Clinic, Live Science
