Over the last decade you’ve no doubt heard that “sitting kills” — a phrase meant to scare you into overhauling your sedentary lifestyle in hopes of adding years to your life.
If you’re a long-time reader then you know I’m all about being as active as you can be whether you’re young or in your golden years, but today I thought we’d take a look at the logic behind leveling a murder charge against sitting.
Just how dangerous is it to merely sit too much? Here’s what I found. . .
According to BBC News, a survey showed that most of us spend up to 12 hours of every day sitting on our backsides.
Considering all the screen-based entertainment and work obligations, from computers to tablets to phones to television, it’s not surprising. Add in the average seven hours a day most people spend sleeping, and you’re sedentary 19 hours a day.
Unfortunately, all this sitting really is bad for you.
Sitting is bad for your heart
The scientific evidence against sitting has been mounting for more than half a century. In a 1950s study of bus conductors who stand versus bus drivers who sit, those who stood had roughly half the risk of developing heart disease.
Since then, similarly promising results about standing were found in a U.K. study where volunteers who normally sit all day were asked to stand for three hours a day. Thanks to a combination of glucose monitors, heart rate monitors, and accelerometers (measures movement and intensity), their measurements revealed that, following a meal, blood glucose levels fell back to normal much faster on the days when the volunteers stood. Plus, the volunteers burned a lot more calories—about 50 an hour. Add that up over a year’s time and it amounts to losing a whopping eight pounds of fat.
And the 2018 Physical Activity Guidelines Advisory Committee Scientific Report (2018 PAGAC Scientific Report) concluded there was strong evidence that high amounts of sedentary behavior increased risk of death from heart disease and type-2 diabetes.
Most recently, a study published in the journal Medicine & Science in Sports & Exercise this year pointed out the risks that sitting poses to your heart.
Why is sitting so bad for you?
Some studies show that sitting is so bad for us, it cuts our longevity by two years. And you can’t necessarily combat these effects with regular exercise. Exercise helps, sure, but prolonged sitting is damaging in ways that can’t be undone.
For example, sitting changes the way your body metabolizes sugar, meaning the way it breaks food down into glucose that gets moved through your bloodstream to other cells. Your body is more efficient at doing this when you’re more active.
Sitting’s effect on sugar metabolism is especially relevant to the development of cancer.
How high blood sugar causes cancer
Cancer has a “sweet tooth,” as long-timer readers of this newsletter know. Over 20 years ago, Dr. Patrick Quillin wrote about the concept that sugar feeds cancer in an issue of Nutrition Science News.
Quite a bit of additional evidence shows cancer is sensitive to blood-glucose levels. One four-year study in the Netherlands found cancer risk more than doubled when sugar intake was high.
In other studies, sugar intake has been shown to be a strong risk factor for breast cancer. And when it comes to virtually any cancer, blood glucose is the preferred fuel. Take sugar out of the picture and most cancer patients see their tumors slow and their prognosis improve.
High blood sugar levels over a long period of time translate into a slew of other health issues, including diabetes, heart attack, stroke, blindness, nerve damage, kidney failure, gum disease, and even tooth loss.
But sitting does more than
just raise your blood sugar
Prolonged sitting also reduces the activity of the enzyme lipoprotein lipase. That’s the substance your body uses to break down fats so they’re available as fuel to your muscles. Reducing this enzymatic activity means you develop elevated triglycerides and fats, incur an increased risk of heart disease, and experience a general sluggishness that leads to less and less physical activity.
That 2018 PAGAC Scientific Report also directly linked sitting with cancer development. The report concluded there was moderate evidence linking all sedentary behavior to cancers of the endometrium, colon, and lungs. Of course, many alternative cancer doctors will tell you that being sedentary will increase your risk of ALL cancers. The report also pointed to evidence that sedentary behavior can increase the risk of dying from cancer if you do get it.
The bottom line here is that simple movements, like standing a few hours a day, help keep your blood-sugar under control. And with your blood sugar under control over the years to come, your risk for several debilitating diseases—cancer among them—plummets nicely.
What you can do
Simple ways to gain the health benefits of standing include pacing while you’re on the phone, opting for a standing table at a coffee shop, or setting a timer every time you sit down to remind yourself to get up and move around at least every half hour.
There are also standing desks you can invest in for your home office or at work. You can also make it a goal to stand whenever possible. A good way to look at it is that the total number of hours spent sitting aren’t as damaging as the number of consecutive hours spent sitting. In other words, your goal should be to interrupt your sedentary time as often as possible.
A five-minute walk can help
The study published this year in the journal Medicine & Science in Sports & Exercise found that a five-minute light walk every half-hour was the only strategy that reduced blood sugar levels substantially when compared to sitting all day.
In fact, these five-minute walks every half-hour reduced by almost 60 percent any blood sugar spike that followed eating. That’s pretty incredible. In addition, this simple walking strategy also reduced blood pressure by four to five points when compared with sitting all day.
Don’t have five minutes? Shorter and less frequent walks improved blood pressure in this study, too. Even just a brief one-minute light walk every hour reduced blood pressure by five points. You can do this around the house, the office or up and down your driveway or street.
Then, there are the mental-health benefits. During the study, participants reported that a five-minute light walk every 30 minutes reduced fatigue, improved mood, and energy level. If you can’t walk every 30 minutes, walking every hour resulted in similar mental health benefits.
If you’re a long-time reader, then you know I’m a big fan of walking. And this new research only adds more fuel to my fire to get out and walk. So, if you want to improve your heart health, reduce your blood sugar, and lower your risk of several cancers, I encourage you to make walking part of your daily exercise routine.
- “7 Ways Sitting Will Kill You.” By Shaunacy Ferro for Popular Science, 25 February 2013.
- “Calorie burner: How much better is standing up than sitting?” BBC News Magazine. 16 October 2013.
- “Cancer’s Sweet Tooth.” By Patrick Quillin from Nutrition Science News, April 2000.
- “Sitting Kills, Moving Heals.” By Dr. Mercola, Mercola.com: 23 June 2013.
- “Why sitting all day is killing you.” By Dave Johnson for CBS News Moneywatch, 23 July 2012.