I recently wrote about Sitting Yourself to Death and touched on the effects of being sedentary. The topic deserves more than a single blog post. You’ll probably be seeing a lot posts in the future as the lack of activity we get is a pretty serious health issue. It’s not that being sedentary keeps us from burning a few extra calories. The act of sitting for extended periods of time actually changes the physiology in the body.
The World Health Organization estimated the number of obese individuals worldwide in 2006 as ~400 million. They predict the total will be 700 million by 2015. 2009 totals for type II diabetes were 200 million and expect numbers to double between the years 2000 and 2030. The numbers are simply staggering. At Life Time Weight Loss, we see the need to attack this epidemic through five key physical areas: Nutrition, Stress & Sleep, Metabolic Health, Exercise and Movement. A lack of movement seems to do a lot more damage to the body other than making us less flexible and causing us to burn a few less calories each day.
A conservative estimate says 55% of Americans’ waking hours are spent being sedentary. Assuming someone gets seven hours of sleep each night, 55% of the remaining time means the average person is sedentary for 9.35 hours per day. As you’ll see below, the remaining 45% of time for most people doesn’t include a very high level of activity either.
Another way to look at the issue of sedentary lifestyles is the vast difference between peoples’ perceptions of how active they are and the reality of their levels of activity. Sixty-five percent of Americans in the NHANES study said they were “active,” but according to studies done by actually measuring activity, only 5% of the population is actually active. Again, two out of three people think they’re active, but only one out of twenty actually are!
Why is there such a drastic difference? Likely, it’s because people are so busy with kids activities, work obligations and errands that they think they’re active. In reality, whether their sitting in the car, sitting at practice or sitting at work, they’re still sitting for most of their day.
How bad is sitting?
Growing evidence suggests that inactivity is a cause of obesity, insulin resistance, dyslipidemia, type 2 diabetes, hypertension and other metabolic diseases. This is the case even for those who meet general exercise guidelines, meaning exercising for an hour 3-5 times per week may not offset the negative health effects of being sedentary the rest of the day. In addition, sitting or being sedentary appears to still cause these issues when individuals follow a good nutrition plan.
Decreased Insulin Sensitivity
Just one day of sitting has been shown to result in a 39% reduction in insulin action, which means the body must produce more insulin than normal to keep blood sugar levels steady. As insulin levels rise, the storage of fat increases and reliance on carbohydrate increases. As the body becomes more of a sugar-burner, triglycerides also increase. Without activity, the body isn’t able to clear triglycerides from the blood as well. Since the muscular system is not challenged with movement, it has no use for the triglycerides floating around in the blood stream.
Altering of Genes
Bed rest studies closely resemble the levels of activity in those who are sedentary. Bed rest has been shown to alter more than 4500 genes and 34 metabolic pathways that determine how well the body’s cells function! To me, this was one of the most amazing statistics in the dozen research articles I read for this blog post. 4500 genes get altered by being sedentary! If genetics play a role in our health, it may very well be a result of what we do to our genes, not what our genes do to us.
Increased Abdominal Fat
Abdominal fat, or visceral fat, increases with inactivity, even when calorie intake is controlled, showing that fat can accumulate outside the “calorie balance” paradigm. It appears this increase in fat mass takes place as a result of increased fat cell numbers rather than increased fat cell size. This also tells us that good nutrition alone may not prevent the development of inflammatory belly fat.
Decreased Fat Burning | Increased Carbohydrate Burning
Fuel utilization shifts to carbohydrates while at rest rather than fat. This also takes place even if calorie intake is limited. Though low-intensity activity like long-duration cardio favors fat utilization, inactivity or being sedentary shifts the body away from using fat and toward the use of carbohydrate, likely as a result of rising insulin levels.
Defying the Logic of Calories In, Calories Out
Rats can voluntarily run up to 20 km per day when provided a wheel to run on. When the wheel is locked, preventing them from running, they see a dramatic increase in fat storage in just 3-4 days. Calories in, calories out advocates would be quick to suggest the fat gain is a result of the rats continuing to eat the same volume of food while significantly reducing their activity levels, resulting in an excessive energy balance. Interestingly, researchers also looked at the effects of limiting rats activity level and then reduced their food intake at the same time to eliminate the chance they’d eat too much. The results in fat gain were exactly the same! It’s another example of why fat loss and fat gain is not just a result of calorie balance, but is more a result of the body’s hormonal environment and how it affects the ability to manage fat and carbohydrate.
A similar study was done on healthy young men. These men averaged at least 10,000 steps per day prior to their study, and then had their activity level reduced to just 1500 steps per day for two weeks. The men lost body weight, so they weren’t eating excessive amounts of food. However, they experienced an average 7% increase in visceral fat, a reduction in insulin sensitivity and they responded worse to glucose and fat tolerance tests. Cardiovascular function (VO2 Max) was also reduced by 7% and leg muscle mass was reduced by 2.8%. Again, these changes occurred in just two weeks! Imagine the impact a new job with a lot of desk time has over a period of months. It’s no wonder so many white collar workers experience such dramatic changes in the condition of their bodies.
As the study authors explained, “Reduced insulin sensitivity leads to larger insulin responses and in some cases larger glucose responses after every meal. Insulin promotes lipid synthesis (fat storage), and therefore, elevated insulin responses following each meal could promote greater fat deposition in adipose.” The bottom line is, people don’t become fatter because they’re burning fewer calories by being sedentary. They get fatter because they actually change, or disrupt, the health of their metabolism.
Movement is not Exercise
Those who are avid fitness enthusiasts may assume that moving more means “exercising” more. In fact, those who exercise more tend to spend more time sitting the rest of their day than those who don’t exercise. Think of exercise as what you do for an hour to optimize your health. Movement is what you do throughout the day just to maintain basic metabolic health.
Movement can be an easy walk following a meal, which has been shown to reduce glucose levels following a meal. Lower glucose levels mean improved fat burning. Researchers found that by having people walk for just 15 minutes following a meal, it reduced the glucose effects the meal. The study participants weren’t moving too fast during the 15 minutes, either.
Exercise is a planned, focused, higher-intensity period of activity. For most people, it occupies an hour of their time three to five days per week. Movement occurs during the remaining 23 hours of the day that aren’t taken up with sleep. As I wrote about previously, I didn’t realize how little I moved myself until I started measuring it. It was a great wake-up call for me even though I don’t miss more than a workout or two each year.
Outside of exercise, the most common way we move is by walking. Counting steps is the most universal way of measuring movement, and a variety of pedometers and activity monitors help to measure the number of steps individuals take each day. Researchers have identified general levels of activity according to the table below.
Walking 10,000 steps per day has been shown to be an effective means of reducing blood pressure. However, those most likely to be impacted by high blood pressure fall quite short of the 10,000 step per day target. Adults 65 and older averaged just 6565 steps per day, putting them at a “low active” level of activity.
Women exceeding 7500 steps/day had a 50% less chance of depression than those taking less than 5000 steps per day. Men who exceeded 12,500 steps had a 50% less chance of developing depression than those at less than 5000 steps per day.
If you remember from the beginning of the article, our perception of how active we are is quite different than our reality. The best way to know you’re getting in enough steps is to wear an activity monitor, at least until your habits change. Studies using 10,000 steps per day as a target, and using an activity monitor to track daily steps, have been the most effective means of increasing activity levels of participants. We chose to offer Fitbits at Life Time for a variety of reasons I won’t go into right now. If you choose to use something else, just make sure you understand the goal is to change your habits throughout the day, not just hit a 10,000 step target through a fast-paced run at the beginning or end of your day.
Step it Up
Achieving 10,000 steps for the day may not be as glamorous as beating your best 10k time, achieving a new personal record on the deadlift or keeping up with your favorite group fitness instructor, but it’s a daily achievement that can have a long-lasting impact. The key is that it must be done daily. You can’t save it up and hit 30,000 steps by spending a Saturday afternoon walking on the treadmill. At this point, there doesn’t seem to be a significant benefit in trying to significantly exceed that number either. 10,000 steps seems to be the target that has the most health benefits for the most people. If you’re up for the challenge, join our Life Time Weight Loss Fitbit group and try to keep your daily average above 10,000 steps.
Have you started tracking your steps? If so, what have you noticed? Share your thoughts and observations below.
This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.