Skip to main content

Why Sitting Is Dangerous for Your Health (and What to Do About It)

This is the fourth installment in our Exercise series.In the Series, we are exploring the real truth about how much (and what kind) of exercise you need as well as the link between diet and exercise. Today we will address an issue that touches us all—why too much sitting can be dangerous for your health!

We simply sit too much.

Pretty much all of us.

According to recent research, 60% of people worldwide spend more than three hours a day sitting down. On average and across all countries, we sit a whopping 4.7 hours a day.

That’s definitely a lot of sitting time!

And even more alarming, scientists universally agree that prolonged periods of uninterrupted sitting are seriously bad for our health.

People who sit too much are more likely to have chronic health problems and die prematurely.

Many health professionals believe that ‘sitting is the new smoking’; it is estimated that over sitting contributed to 433,000 deaths every year from 2002-2011.

In this fourth article in our exercise series, we will explore the problem of sitting too much and how to say goodbye to our sedentary lives once and for all.

Too Much Sitting=a Shorter Life?

There is growing scientific consensus that the more time someone spends sitting, the shorter and less robust his life will be.

Study after study associate prolonged sitting time with an increased risk of obesity and type 2 diabetes, cardiovascular disease, other metabolic disorders, and premature death.

Upon evaluation of medical records and lifestyle questionnaires of more than 220,000 Australian adults 45 and older, researchers found that those who sat more than 8 hours a day had 25% greater risk of all-cause mortality than those who sat fewer than 4 hours a day.

Very similar results were reported in an American Cancer Society study, which tracked the health of 123,000 Americans from 1992-2006. The men in the study who spent 6 or more hours a day sitting had a 20% higher death rate than those who sat for 3 hours or less while women who spent 6+ hours sitting had a 40% higher death rate than their more active female counterparts!

In another review of 18 studies analyzing over 800,000 participants, sedentary time is associated with an increased risk of cardiovascular disease, all-cause mortality, and type 2 diabetes (with the association being the highest for diabetes).

While these studies associate sitting with health risk (versus demonstrating plain cause and effect), their message is nevertheless evident. As Dr. James A. Levine of the Mayo Clinic and leading researcher in the field of inactivity studies says, “Excessive sitting is a lethal activity.”

That Hour in the Gym Cannot Fix Things…

Many believe that the negative effects of sitting can be offset through daily exercise.

Nothing could be farther from the truth.

The research is crystal clear… you cannot ‘cancel out’ the ill effects of sitting through a daily exercise regime. That is because time spent sitting is “independently associated with total mortality, regardless of physical activity level.”

If you spend the bulk of your day sitting (in your car, at the office or on your sofa), you are still putting yourself at risk for obesity, type 2 diabetes, cardiovascular disease, different types of cancers and an early death—even if you run every morning or hit the gym every day.

A 12-year Canadian prospective study demonstrated a dose-response association between sitting time and mortality from all causes and cardiovascular disease, which was independent of whether or not the participants exercised regularly.

Because your daily exercise cannot ‘protect’ you from the health risks of sitting for extended periods, you need to be mindful of what you do during your non-exercise time. Assuming you exercise for 30-60 minutes a day and you sleep for 8, you still have 15-15.5 hours left. During those remaining hours, you need to move and be as physically active as possible. And sit as little as you can.

(Later in the article, we will give you some tips on how to do that.)

What Does All That Sitting Do to Your Body

As we have discussed, scientific evidence has linked excessive sitting with a number of health problems including obesity, increased blood pressure, high blood sugar, abnormal cholesterol levels, excess body fat around the waist, cardiovascular disease, cancer and premature death.

But the question is why?

There appears to be a ‘physiology of inactivity’.

When you are physically active, your muscles contract, producing substances that improve how your body uses and stores sugars and fats. When you are inactive, this process is stalled, leading to a cascade of negative metabolic effects.

In a research experiment, participants were men who normally walked a lot (around 10,000 steps a day). When they reduced their activity to about 1,350 steps per day for 2 weeks, all of them began to experience difficulties metabolizing sugars and fats. At the same time, their body fat shifted and they became fatter around the middle.

Another study mirrored these results. All participants were sitting for many hours a day, however, half of them took frequent small breaks to walk or stretch while the other half remained sitting. At the end, the group who took breaks had much smaller waists and better sugar and fat metabolism compared to those who sat uninterrupted.

When your body is inactive, many physiological processes dramatically change including:

  • Fewer Skeletal Muscle Contractions. When muscles do not contract, they require less fuel. The surplus blood sugar then accumulates in the bloodstream, increasing the risk of diseases like type 2 diabetes.
  • Disruption of Enzyme Production. Researchers have shown that after an hour or more of sitting, the production of enzymes that burn fat in the body declines by as much as 90% and causes the levels of good (HDL) cholesterol to fall.
  • Lower Calories Consumed. When you sit for long periods of time, your calorie-burning rate plunges to about 1 calorie per minute, 30% of what it would be if you got up and walked. All that sitting logically increases the risk of obesity.
  • Reduction of Insulin Effectiveness. In a study of young fit men, a 40% reduction in insulin’s ability to uptake glucose was reported a mere 24 hours after they the subjects became sedentary. This dramatic drop in insulin effectiveness is associated with an increased risk of developing type 2 diabetes.
  • Overstimulation of the Sympathetic Nervous System. Being sedentary may cause neurons in the brain to sprout new branches that are more sensitive to stimuli. This potential overstimulation of the sympathetic nervous system may increase blood pressure and contribute to the development of heart disease.

How to Fix It?

When you sit for long periods of time, you fail to properly break down the fats and sugars you eat. You put on weight. You disrupt enzyme production and insulin activity. You increase your risk of a range of chronic diseases.

By standing or actively moving you kick all these ‘stalled’ processes back into action.

However, it is important to stress that you can achieve positive results even with simple (and small) changes. Just a few minutes per hour of moving (versus sitting) could substantially reduce your health risks while going for a gentle walk for two minutes each hour could lower your risk of premature death by 33%!

The impact of increased movement—even if it is leisurely—can be profound.

Here are some specific ideas of how we can all spend a lot less time in our chairs:

  1. Cut TV time. Four hours a day is ‘risky’ while anything less than 2 hours per day is considered to be a lower risk.
  2. Stand Up. If you can use a standing desk for reading, checking your email or paying bills. Stand up (and maybe walk around) during phone calls. Hold ‘standing up’ meetings.
  3. Use a Treadmill Desk. Even better, slide a treadmill underneath your standing desk an you will get your 5 miles a day walking before you leave the office!
  4. Take Walking Breaks. If standing up or walking on a treadmill is not an option for you, consider spending 5-10 minutes every hour walking a short distance. It will add up.

You may also want to take another look at our recent article which includes some fresh ideas about how to get your 10,000 steps a day, whether you can walk 3-5 miles or not.

Is Standing Enough?

I have frequently been asked why ‘standing’ is not considered a sedentary activity like sitting.

Standing up—even if you are standing still—is much better for you than sitting. In fact, compared to sitting, standing is hard work because you engage your leg muscles as well as your back and shoulders.

Research substantiates this. In one analysis, absolutely no link was found between standing and premature deaths (unlike sitting where there is a clear association with increased mortality). Furthermore, higher levels of standing have even being associated with declined mortality rates.

An interesting Swedish randomized clinical trial showed that avoiding sedentary behavior might lengthen your telomeres.

Telomeres are the tiny caps on the ends of DNA strands, which shorten and fray as a cell ages. Longer telomere lengths are associated with healthier lifestyles while shorter lengths are often linked to illness and obesity.

Interestingly, the telomeres lengthened in the group that sat the least; their cells seemed to be growing physiologically younger. Once again, telomere length and exercise did not seem to correlate. Those who worked out the most but sat more had shorter telomeres compared to the group that exercised less but stood more (and sat less).

It is clear that too much sitting is not good for us. And while our technology driven society has most of us plunked all day in front of screens, the good news is that just by moving around and standing a bit more, we can overcome the effects of sitting.

So maybe it is time to start. Today.

Let’s all make a vow to sit less, stand up and get moving!

Rosane Oliveira, DVM, PhD

President & CEO, Plant-Based Life Foundation | Dr. Rosane Oliveira combines a lifelong passion for nutrition with 25 years of genetics research to create programs that help people develop healthy habits on their journey towards a more plant-based lifestyle. She is a Visiting Clinical Professor in Public Health Sciences and was the founding director of the first Integrative Medicine program at the UC Davis School of Medicine. She completed her postgraduate studies in Brazil and did her postdoctoral training in immunogenetics and functional genomics at the University of Illinois at Urbana-Champaign.