Is Sitting Really the New Smoking?
ORIGINAL POST BY HVMN
Are you sitting at your desk reading this? Maybe you’re reading this while standing at your desk. It seems both, in one way or another, can kill you.
That’s a bit hyperbolic. But the sentiment is shared with claims made across the internet, that “sitting is the new smoking” and can lead to serious health risks. And since many of us sit at work dozens of hours a week—we are at risk. These claims speak directly to many of us. Before diving into the science behind sitting, let’s first analyze the claim itself: is sitting REALLY the new smoking? Can the two even be compared?
Why is Smoking Bad For You?
Dr. James Levine of the Mayo Clinic is credited with coining the phrase, “sitting is the new smoking.” In a LA Times interview, he went even further: "Sitting is more dangerous than smoking, kills more people than HIV and is more treacherous than parachuting. We are sitting ourselves to death."
But how is sitting comparable to smoking in the first place?
According to the American Cancer Society, nearly 500,000 Americans die every year from tobacco-related causes. Two poisonous ingredients in tobacco are affecting people's health: carbon monoxide and tar. Carbon monoxide, found in car exhaust fumes, is fatal in large doses, replacing oxygen in the blood, starving organs of oxygen. Tar is a sticky brown substance coating lungs and impairing breathing.
You know smoking is bad. But how bad is it, exactly?
Impaired Lung and Respiratory Function
This one feels obvious; lung and respiratory problems are often just the start. Decrease in lung function is likely linked to the damage smoking causes to the airways and air sacs of the lungs.
Smoking decreases lung function, and causes lung cancer 1,2 There is no question, according to the study: “The magnitude of the excess lung-cancer risk among cigarette smokers is so great that the results can not be interpreted as arising from an indirect association of cigarette smoking with some other agent or characteristic.”
Smoking can also cause chronic obstructive pulmonary disease (COPD),3 which is a collection of lung diseases including bronchitis and emphysema. Those with this condition have difficulty breathing, mostly through the narrowing of airways and destruction of lung tissue.
Weakening of the Heart and Blood Vessels
One meta analysis showed smoking increases the risk for stroke.4 Poisons in cigarettes can lead to blood clots, damage blood vessels and lead to a buildup of plaque, all causing disruption of blood flow to the brain and leading to a stroke.
Heart disease is also closely linked with cigarette smoke, damaging the function of the heart by increasing the risk of atherosclerosis (when plaque builds up in the arteries).5 This limits the flow of oxygen-rich blood to vital organs and other parts of the body. With this plaque buildup can come heart disease, heart attack, heart failure and even death.
When combined with other risk factors for heart disease—unhealthy cholesterol, high blood pressure, obesity—smoking can further increase risk of heart disease.
Decline in Cardiovascular Health
Because smoking causes plaque buildup in the arteries and blood vessels (narrowing them), this reduces blood flow and increases the risk of clotting. Of course, these are also linked with heart disease associated with smoking.
Cigarette smoke significantly contributes to cardiovascular disease.6 Even secondhand smoke can predispose cardiovascular events.6 This is largely due to the toxins in cigarettes, which increase inflammation, thrombosis and oxidation of LDL cholesterol (the bad kind of cholesterol). The result? Oxidative stress as a potential for negatively impacting cardiovascular health.
Because sitting has been linked to heart disease, this might be where the association started.
Sitting, Smoking and Your Health
The hype for “sitting is the new smoking” is very real. One study cited 300 news articles mentioning the claim.7
25% of adults sit more than eight hours per day,8 with older adults usually sitting for more time. Even with a sedentary lifestyle, is it fair to compare sitting to smoking?
Why is Sitting Bad for Health?
Let’s be clear about this: sitting isn’t good for you. But the question remains: is it as bad as smoking?
When compared with lower amounts of sitting (less than four hours per day), higher volumes of sitting (greater than eight hours) can have negative outcomes on your health. Generally, health concerns associated with sitting include: cardiovascular disease, all-cause mortality, cancer, and diabetes.
Data shows a strong correlation between sitting for high volumes and diabetes.9 Sitting can increase the risk of diabetes by 2x. Associations with cardiovascular disease, cancer, and all-cause mortality aren’t as strong but still present.9,10 Furthermore, sedentary lifestyles have also been associated with higher risk of depression.11
Generally, the data is less concrete when compared to how smoking impacts overall health. In terms of the concerns around major health problems and mortality, it appears sitting may only increase these risks by 10% - 20%. Sitting can lead to more minor (relatively) health problems related to obesity and back, neck and sciatica pain.
But most people agree with Dr. Terry Boyle, a researcher from the University of South Australia, who made it clear: “The simple fact is, smoking is one of the greatest public health disasters of the last century. Sitting is not, and you can’t really compare the two.”
Despite Dr. Boyle’s assertion, let’s explore the science a bit more.
Connection Between Sitting and Smoking
People draw parallels between sitting and smoking because of the results, not the mechanisms of action.
One study showed daily sitting volume and amount of prolonged sitting have been associated with increased mortality (smoking also causes increased mortality).12 However, a response to the study noted that exactly how sitting negatively impacts health is “unclear and complex.” 13 Some theorize that sitting for extended periods of time and for many hours a day can reduce insulin sensitivity; others believe net calorie expenditures decline too.
Another surprising study showed the association between sitting and cancer; in the study, those with the highest levels of sedentary behavior had significantly increased risks of colon, endometrial and lung cancers.14 This research also suggested that time spent sitting can be detrimental even to those who are otherwise physically active.
However, the study notes its own limitations: “TV viewing time showed the strongest relationships with colon and endometrial cancer, possibly because...TV watching is often associated with drinking sweetened beverages, and eating junk food.” This underscores the complexities of associating cancer with any one behavior (well, besides smoking cigarettes).
Largely, the connection made by the popular media between sitting and smoking is based on the fact that both might be seen as widespread health risks. Sitting might be a surrogate marker for a much broader social problem: physical inactivity. This physical inactivity absolutely has correlations to some of the health risks associated with smoking, but again, through very different means.
In short, it seems that how sitting contributes to poor health is unclear—but the dangers of a physical inactive, sedentary lifestyle have been well-documented.
Standing for Change
It’s unlikely you’ll just drop dead from sitting at your desk, but you still should be taking measures to reduce inactivity. There’s no doubt that sitting too much isn’t healthy.
A big change sweeping workplaces across the country is standing desks. But before standing to attention, there have been studies that say standing can be detrimental to health, too.
Standing for prolonged periods can have detrimental musculoskeletal effects on the lower back and lower extremities.15 In even more grim news, one study showed that predominantly standing occupations were associated with a 2x risk of incident heart disease (compared to those with predominantly sitting occupations).16 Just like sitting, standing all day may have adverse effects.
So really, it’s the act of moving that can be beneficial for your health. Getting up from your desk and moving every 30 minutes reduces that early all-cause mortality rate.12 Those desks that give you the option to sit or stand may be the answer.
A meta analysis showed an ability to change behavior, encouraging people to stand more frequently. Some participants who used sit-stand desks were found to have slightly lower blood pressure and a slightly elevated heart rate, which is considered good for health.17 There’s also an element of overall comfort, noting that a small group of people experienced improvements in lower back pain by incorporating both standing and sitting.
However, what this comes down to is the need for movement. According to federal government guidelines, adults need a minimum of 150 minutes per week of moderate-intensity physical activity.
The updated federal guidelines also had an interesting addition: move more, sit less.
Some studies show that even just 30 minutes a day of physical activity can counteract some of the effects of sitting.18 But the data is extremely mixed. A meta analysis showed that 60 minutes of physical activity a day might reduce some of the effects of sitting,19 while another study showed the same amount of physical exercise doesn’t undo how sitting can negatively impact insulin and blood fats.19
While physical activity may not counteract the negative effects of sitting, it’s still important to be moving throughout the day.
Final Word on Sitting as Smoking
Sitting is not the new smoking. It’s almost unfair to compare the two, despite data that points to the negative overall impact of sitting on health.
The comparison is meant to underscore the widespread potential danger of a sedentary lifestyle. It’s likely more people sit for more than five hours a day than smoke cigarettes. This is illustrative of the population’s general shift to a new type of work, a new type of lifestyle.
The point? Get moving. By increasing physical activity throughout the week (and even moving throughout the day, at your desk), you’ll probably be better off. Just don’t use that as an excuse to walk around the block for a smoke break.