Sitting isn’t the new smoking, but long TV evenings still carry risk

Key takeaways

• In 2015–2016, U.S. adults said they sat about 6.4 hours a day, up from 5.5 hours in 2007–2008, and 65% watched TV or videos at least 2 hours a day⁵.
• Across 34 studies of more than 1.3 million adults, the risk of early death climbed faster above about 6 to 8 hours of total sitting, or 3 to 4 hours of TV, a day⁷.
• Sitting is not as dangerous as smoking: heavy smokers have about four times the death risk of people who never smoked, while sitting more than about 8 hours a day raises it an estimated 10% to 20%⁹¹⁰.
• The World Health Organization tells adults to limit sitting and replace it with movement of any intensity, even light, but it sets no hourly limit¹¹.
• In a 2024 trial, older adults who sat about 32 fewer minutes a day lowered their top blood pressure number by about 3.5 points compared with a control group¹³.

In a classic study published in 1953, British researchers compared two jobs on the same double-decker buses⁶. The drivers sat through almost all of a 5.5-hour shift. The conductors kept climbing the stairs⁶.

Jobs heavy in sitting, such as driving a bus, went with about twice the rate of cardiovascular disease, a 2007 University of Missouri review noted⁶.

Today, many of us live more like the drivers. In 2015–2016, about one in four U.S. adults said they sat more than 8 hours a day⁴.

Then came the slogan “sitting is the new smoking.” By one researcher’s count, media coverage making that comparison multiplied twelvefold over four years, from 2012 to 2016¹⁰. The comparison went too far. But long sitting does carry real risk, and some of it remains even in people who exercise³⁷.

Our article on full-time work covers the desk. This one covers the rest of the day: the car, the couch and the screen.

Sedentary and inactive are two different problems

The Sedentary Behaviour Research Network, an international group of scientists, defines sedentary behavior as any waking activity done sitting, reclining or lying down that burns 1.5 METs or less¹. A MET is a multiple of the energy your body uses at rest, so 1.5 METs is barely above resting³.

Watching TV, playing video games, using a computer, reading and driving all count¹. Sleep doesn’t count, and neither does standing, even standing still¹²³.

Physical inactivity is something else. It means not getting enough moderate-to-vigorous activity to meet the guidelines². The two don’t track closely: you can meet the guidelines and still sit most of your waking day².

National data show both. In 2015–2016, 25.7% of U.S. adults sat more than 8 hours a day, 44.6% got no moderate or vigorous leisure activity, and 11.4% had both habits⁴.

Picture a reader who runs at 6 a.m., drives to a desk job and spends the evening on the couch. She is active and highly sedentary at the same time.

Americans sit more each decade

One of the longest looks comes from a national health survey that included 51,896 Americans from 2001 to 2016. Researchers led by Lin Yang published the trends in JAMA in 2019⁵.

Total sitting rose for adults from 5.5 hours a day in 2007–2008 to 6.4 hours in 2015–2016⁵. Teens went from 7.0 to 8.2 hours⁵.

The mix shifted, too. Adults using a computer an hour or more a day outside work rose from 29% in 2003 to 50% in 2016⁵. TV held steady for working-age adults, but 84% of adults 65 and older watched at least 2 hours a day by 2015–2016⁵.

These are self-reports, and the TV question gave inconsistent answers when people were asked twice⁵. Movement monitors don’t rely on memory. In monitor data cited by the federal activity guidelines, children and adults logged about 7.7 sedentary hours a day, about 55% of their waking time³.

When you sit, your leg muscles go quiet

The Missouri team’s 2007 review, published in the journal Diabetes, gathered what sitting does inside the body⁶. One recording in it shows a leg muscle’s electrical signal going silent as a person sat, then firing again when they stood⁶. Even quiet standing takes muscle work, and standing or slow walking raises the body’s energy use roughly 2.5-fold over sitting still⁶.

Daily movement outside exercise burns as little as about 300 calories in chair-bound people and about 2,300 in people whose days include some manual labor⁶.

The team’s animal work went deeper. When rats were kept from standing and walking, an enzyme called lipoprotein lipase dropped sharply in their hardest-working leg muscles⁶. This enzyme helps muscles pull fat out of the blood to use as fuel.

Activity of the enzyme fell to about 10% of normal within 12 hours, and HDL, the “good” cholesterol, ran about 20% lower⁶. Brief standing and very slow walking brought the enzyme back within 4 hours⁶. Running, by contrast, raised it in different muscle fibers⁶.

That led the authors to argue that too little daily movement and too little exercise are separate problems⁶. Keep the limits in mind: the enzyme findings come mainly from rats, and the human evidence is mostly observational⁶. The work was funded by the National Institutes of Health⁶.

TV time looks worse than other kinds of sitting

In 2018, researchers led by Richard Patterson pooled 34 long-term studies of more than 1.3 million adults⁷. British public and charity funders paid for it, not industry⁷.

For total sitting, the risk of death from any cause climbed faster above about 8 hours a day. For heart disease deaths, the turn came at about 6 hours⁷. For TV, the curve steepened above about 3.5 hours for death from any cause and about 4 hours for heart deaths⁷.

Hour for hour, TV carried more risk. Each extra daily hour of TV went with about a 9% higher risk of type 2 diabetes, compared with about 1% for each hour of total sitting⁷. Accounting for how active people were shrank these links, more for TV than for sitting overall⁷.

The brain may show the same split. In a 2022 study of more than 145,000 adults 60 and older in the United Kingdom, followed for nearly 12 years, more TV time was linked to a higher risk of dementia⁸. More computer time was linked to a lower risk, and both links held after the team accounted for how physically active people were⁸. The NIH-funded team suspects TV takes less muscle work and less thinking than computer use⁸.

One caution: these studies observed people rather than assigning them to sit, and people who are already unwell may watch more TV. Our article on observational studies explains why such links can mislead.

Sitting isn’t the new smoking, but the numbers show why

In 2018, nine researchers from Canada, the United States and Australia tested the slogan in the American Journal of Public Health⁹¹⁰.

Smokers have nearly three times the risk of dying from any cause as people who never smoked, and people who smoke more than 40 cigarettes a day about four times⁹. Sitting more than about 8 hours a day goes with roughly a 10% to 20% higher risk of early death¹⁰. Smokers’ risk of lung cancer rises more than tenfold¹⁰.

In absolute numbers, the gap is starker. Among the heaviest smokers, the authors estimated more than 2,000 extra deaths per 100,000 people each year⁹. For the most sedentary people compared with the least, the figure was about 190⁹.

Unlike smoking, sitting isn’t addictive and doesn’t harm bystanders¹⁰. The authors warned that inflated slogans can confuse people and wear down trust in health advice⁹.

That matters to readers who already question official messaging. Long sitting is worth fixing, not panicking over.

The guidelines say sit less, but give no hourly limit

The WHO’s 2020 guidelines tell adults and older adults to limit the time they spend sedentary¹¹. Swapping sitting for movement of any intensity, even light, brings benefits. The WHO calls that a strong recommendation based on moderate-certainty evidence¹¹.

People who sit a lot should aim for more than the standard weekly amount of moderate-to-vigorous activity¹¹. The same advice covers people with chronic conditions or disabilities, on less certain evidence¹¹.

The federal Physical Activity Guidelines, issued in 2018, say adults should “move more and sit less”³. Their expert committee found strong evidence linking sedentary time to deaths from any cause and from heart disease. They couldn’t set a sitting limit because the risk depends on how active a person is³.

High amounts of activity appear to erase the extra death risk of heavy sitting, and for inactive adults, trading sitting for light activity lowers risk³. Our article on full-time work describes how much activity that takes.

Kids and screens

For ages 5 to 17, the WHO recommends limiting sedentary time, especially recreational screen time¹¹. It rates the evidence as low certainty, but links more sitting in kids to more body fat, poorer heart and metabolic health, lower fitness, behavior problems and shorter sleep¹¹.

Screens fill much of that time. In 2015–2016, 62% of U.S. children ages 5 to 11 watched TV or videos at least 2 hours a day⁵.

The American Academy of Pediatrics (AAP) has moved away from simple hour limits. Its newest policy statement, explained on its parent website in 2026, focuses on what children watch, why, and what screens crowd out, including sleep, play, family time and movement¹². It suggests keeping bedrooms, meals and the hour before bed screen-free¹². Our article for busy parents covers family media plans.

A sitting audit for an ordinary day

Pick one ordinary weekday and one weekend day. For each block below, write down roughly how long you sat and your longest stretch without getting up.

Part of the day	Sitting to look for	Write down	Kind of sitting
Morning and meals	Breakfast, news, phone, devotions, lunch, dinner	Minutes seated; longest stretch	Passive or mind-active
Getting around	Car, bus, train, waiting rooms	Driving counts as sedentary1	Passive
Work or school	Desk, meetings, classes	Total only; our work article covers this block	Either
Evening TV and streaming	Shows, sports, movies	Hours; longest stretch	Passive
Other screens	Phone, games, computer for fun	Hours	Mind-active or passive
Hobbies and visiting	Reading, crafts, cards, talking with friends	Hours	Mind-active
Before bed	Scrolling, TV in bed	Minutes	Passive

Then total it and check three things:

• Your total. If it tops about 8 hours, you’re in the range where risk rose faster in pooled studies⁷.
• Your TV hours. If they top about 3 to 4, TV is your best target⁷.
• Your longest stretch. Long unbroken blocks are the easiest to interrupt.

These thresholds are averages from observational studies, not personal limits.

A home plan to sit less, built on a real trial

In a 2024 trial at Kaiser Permanente Washington, researchers led by Dori Rosenberg enrolled 283 adults ages 60 to 89 who had obesity and sat at least 6 hours a day¹³.

About half received a program called I-STAND for six months: 10 coaching sessions, mostly by phone, a tabletop standing desk and a wrist activity tracker that prompted them to move¹³. The other half got coaching on unrelated healthy-living topics¹³.

The I-STAND group sat about 32 fewer minutes a day than the comparison group and stood about 28 more¹³. Their top blood pressure number fell about 3.5 points more¹³. Weight and waist size didn’t change¹³.

That’s close to what other studies have found for exercise programs (about 4 points) and weight loss (about 3), the authors said¹⁴. Some participants had their tracker buzz every hour. Others made standing part of a daily ritual, like the first cup of coffee or the morning paper¹⁴. The federal National Heart, Lung, and Blood Institute paid for it¹⁴.

This is a home plan built on those lessons. Items marked “untested” are ideas no trial has measured.

Step	What to do	Evidence note
1. Pick two targets	Choose your two longest sitting blocks from the audit	Practical starting point
2. Set a cue	An hourly phone or tracker reminder to stand and move for a few minutes	Used in the I-STAND trial14
3. Stack it on a habit	Stand for your first coffee, the news or phone calls	Used in the I-STAND trial14
4. Raise a surface	Read, sort mail or use a laptop at a counter or tabletop riser	Standing desk was part of I-STAND13
5. Break up TV	Stand, stretch or do a chore between episodes or during ads	Untested; aims at the TV-sitting link7
6. Trade some screen time	Swap one show for cooking, gardening, a walk or play with kids	WHO: any intensity counts11
7. Recheck in four weeks	Redo the audit; aim for 30 fewer minutes a day first	About the drop seen in the trial13

Movement woven into the day

Many natural-health traditions never separated movement from living. People walked to market, hauled water and worked gardens.

The research backs that older pattern: both the WHO and federal guidelines say light movement through the day brings benefits of its own³¹¹. Chores and a walk to the mailbox count.

What the evidence shows

Claim	What studies found	Evidence level
Long daily sitting is linked to early death, heart disease and diabetes	Consistent links in 34 studies of 1.3 million adults; federal experts rated it strong37	Strong evidence (observational)
Plenty of exercise offsets much of the extra death risk of heavy sitting	High activity appears to remove the excess risk, per federal experts3	Strong evidence (observational)
TV time carries more risk than other sitting	Higher risk per hour of TV; TV linked to more dementia, computer use to less; sick people may watch more TV78	Promising but early
Inactivity sharply lowers a fat-clearing enzyme in leg muscle	Large drops in rats; human data mostly observational6	Promising but early
Cutting daily sitting lowers blood pressure in older adults	About 3.5 points in one six-month trial of 283 people13	Promising but early
Limiting kids’ recreational screen time helps health	WHO strong recommendation on low-certainty evidence11	Promising but early
Sitting is as harmful as smoking	Smoking’s risk is many times larger910	Evidence says no

Questions readers ask

The bottom line

Long sitting isn’t tobacco, but it is a real and fixable risk, and TV time is the part with the clearest warning signs. The guidelines ask for less sitting and more movement of any kind, and they don’t set a magic number.

Start with an honest audit of one ordinary day. Then break up your longest sitting blocks with reminders, habits and small chores. In one trial of older adults, half an hour less sitting a day was enough to move blood pressure.

Keep exploring: walking pace and health, cycling health benefits and recreational sports health benefits.

Related reading

• Full-time workers average under three free hours a workday, so build health into the rest
• Busy parents need a few anchors more than a perfect routine
• Fiber, form and a short walk shape how carbs affect your blood sugar
• Why observational studies got smoking right and hormone therapy wrong
• Your heart counts the weekly total while your habits count the repeats

Sources

1. Sedentary Behaviour Research Network. “What is sedentary behaviour?” (on Tremblay MS, et al., “Sedentary Behavior Research Network (SBRN) – Terminology Consensus Project process and outcome,” International Journal of Behavioral Nutrition and Physical Activity, 2017). sedentarybehaviour.org
2. MRC Epidemiology Unit, University of Cambridge. “Sedentary behaviour.” DAPA Measurement Toolkit, accessed October 2026. measurement-toolkit.org
3. U.S. Department of Health and Human Services. “Physical Activity Guidelines for Americans, 2nd edition.” HHS, 2018. odphp.health.gov
4. Ussery EN, Fulton JE, Galuska DA, Katzmarzyk PT, Carlson SA. “Joint Prevalence of Sitting Time and Leisure-Time Physical Activity Among US Adults, 2015-2016.” JAMA, 2018;320(19):2036-2038. pmc.ncbi.nlm.nih.gov
5. Yang L, Cao C, Kantor ED, et al. “Trends in Sedentary Behavior Among the US Population, 2001-2016.” JAMA, 2019;321(16):1587-1597. pubmed.ncbi.nlm.nih.gov
6. Hamilton MT, Hamilton DG, Zderic TW. “Role of Low Energy Expenditure and Sitting in Obesity, Metabolic Syndrome, Type 2 Diabetes, and Cardiovascular Disease.” Diabetes, 2007;56:2655-2667. pubmed.ncbi.nlm.nih.gov
7. Patterson R, McNamara E, Tainio M, et al. “Sedentary behaviour and risk of all-cause, cardiovascular and cancer mortality, and incident type 2 diabetes: a systematic review and dose response meta-analysis.” European Journal of Epidemiology, 2018 (UCL repository). pubmed.ncbi.nlm.nih.gov
8. University of Arizona News. “What older adults do while they sit affects dementia risk, study finds” (on Raichlen DA, et al., Proceedings of the National Academy of Sciences, 2022). August 22, 2022. news.arizona.edu
9. Vallance JK, Gardiner PA, Lynch BM, et al. “Evaluating the Evidence on Sitting, Smoking, and Health: Is Sitting Really the New Smoking?” American Journal of Public Health, 2018;108(11):1478-1482. pubmed.ncbi.nlm.nih.gov
10. University of South Australia. “Sitting is NOT the new smoking, contrary to popular myth” (news release, via ScienceDaily). November 5, 2018. sciencedaily.com
11. World Health Organization. “WHO Guidelines on Physical Activity and Sedentary Behaviour.” WHO, 2020 (NCBI Bookshelf). ncbi.nlm.nih.gov
12. Munzer T, American Academy of Pediatrics. “Helping Kids Thrive in a Digital World: AAP Policy Explained.” HealthyChildren.org, updated June 3, 2026. healthychildren.org
13. Rosenberg DE, et al. “Sitting Time Reduction and Blood Pressure in Older Adults: A Randomized Clinical Trial.” JAMA Network Open, 2024;7(3):e243234. pubmed.ncbi.nlm.nih.gov
14. Kaiser Permanente Washington Health Research Institute. “Changing sitting habits shows meaningful impact.” March 27, 2024. kpwashingtonresearch.org
15. Riebe D, Franklin BA, Thompson PD, et al. “Updating ACSM’s Recommendations for Exercise Preparticipation Health Screening.” Medicine & Science in Sports & Exercise, 2015, as applied in Leeds Beckett University, Carnegie School of Sport, “Health Screening Guidance.” Www.Leedsbeckett.Ac.Uk