Myth or fact

Sitting is the new smoking

Short answerNot the way you think

By GyroscopeUpdated November 14, 20264 sources

Not the way you think. Most of the harm of sitting is the moving you aren’t doing. In more than a million adults, people who sat over 8 hours a day but moved about 60 to 75 minutes a day had no clear extra risk of death. And smoking’s risk is many times larger.

Why it sounds true

It’s a great line, short and scary, and it gets repeated everywhere from office wellness posters to news stories about the modern workday. Some versions go further and claim that sitting is worse than smoking. There’s real science underneath it: long hours of sitting do go with higher risk of death in big studies, and the US guideline’s first line for adults is to “move more and sit less throughout the day.” The line just blows the size of the risk up many times over.

A picture from daily life

Comparing sitting to smoking is like comparing a parking ticket to a car crash. Both are bad news you’d rather avoid. One of them is far bigger, and treating them the same makes it harder to see which one to fix first.

How big is each risk?

In 2018, a group of researchers in the American Journal of Public Health put the numbers side by side. The most recent pooled study of sitting and other sedentary time found about 22% higher risk of death (a hazard ratio of 1.22). Current smokers had about 2.8 times the risk of death of people who never smoked (2.80 for men, 2.76 for women), and people who smoked more than 40 cigarettes a day had more than 4 times the risk.

In real numbers, that’s more than 2,000 extra deaths a year per 100,000 people for the heaviest smokers against people who never smoked, and about 190 extra deaths a year per 100,000 for people who sat the most against people who sat the least. The authors’ conclusion was that sitting and smoking “are not comparable”, and that mixing them up “can lead to confusion and public doubt”.

What happens when you move enough?

The biggest study on sitting, in 2016, pooled more than a million adults followed for 2 to 18 years. In the most active group, about 60 to 75 minutes of moderate activity a day, people who sat more than 8 hours a day had no clear extra risk of death (a hazard ratio of 1.04, with a range that included no difference). The least active people who sat under 4 hours still had 27% higher risk. Sitting less didn’t make up for moving too little, and in the most active group the hours of sitting stopped showing up in the risk. Does a workout cancel a day of sitting?

The first evidence pointed this way 70 years ago. In the early 1950s, Jeremy Morris found that London bus conductors, who climbed the stairs of their double-deckers all day, had less heart disease than the drivers, who sat.

Where the myth has a point

Sitting isn’t harmless. The least active people who sat more than 8 hours a day had 59% higher risk of death than people who sat little and moved a lot. And TV was harder to offset than other sitting. Watching 3 hours or more a day went with higher risk at every activity level except the most active, and even in the most active group, 5 hours or more went with 16% higher risk. A more useful slogan would be to move about an hour a day and turn the TV off earlier.