What Really Happens to Your Body When You Don't Exercise

After a rough day of work or taking care of the kids, it's easy to succumb to the siren song of your comfy couch. And it's becoming increasingly common for people to live a sedentary lifestyle and get little to no exercise.

According to a January 2020 report from the Centers for Disease Control and Prevention, about 15 percent of Americans are physically inactive. The problem is that living like this has a long list of negative health effects.

"There are many types of exercise, and all of them have benefits for your health, and conversely, the lack of each type can have a different negative impact if someone neglects that type," says Lynn Marie Morski, MD, board-certified family medicine and sports medicine physician.

The combination of no exercise and a sedentary lifestyle significantly increases your risk of developing a long-list of life-threatening conditions. "Evidence suggests that a sedentary lifestyle may even more strongly predict mortality than some of the causes with well-known associations to mortality, like smoking and high blood pressure," Dr. Morski says.

Here's exactly what happens to your body when you don't exercise.

Physical activity places a high demand on your heart to pump blood to your working muscles, and many of the benefits exercise provides can be derived from improved cardiovascular health.

"Aerobic exercise has been shown to improve circulation, blood pressure and cardiac output, which is a measure of how well the heart is pumping blood to the rest of the body," Dr. Morski says.

The heart — like any other muscle — responds to the strain from exercise by getting stronger. With no exercise, you aren't providing the stimulus your heart needs to get stronger, and this can worsen your health.

"Increased sedentary time has been associated in recent studies with features of metabolic syndrome, like increased waist circumference and insulin resistance," Dr. Morski says. "It has even been found to have an association with increased cardiovascular disease and all-cause mortality, as well as an elevated risk of type 2 diabetes."

In a February 2019 study published in ​Circulation Research​, researchers found that sedentary behavior is among the leading preventable factors worldwide associated with increased cardiovascular disease and all-cause mortality.

Every part of the body is subject to the effects of aging, and the brain is no exception. Aerobic exercise helps slow brain aging and cognitive decline, according to a January 2020 study published in the ​Mayo Clinic Proceedings​. While with no exercise, your brain may be more vulnerable to the effects of this age-related decline.

Plus, aerobic exercise may help improve memory and learning. In a February 2015 study published in the ​British Journal of Sports Medicine,​ regular aerobic exercise was shown to significantly increase hippocampal volume in elderly women. That suggests actual structural differences between the brains of sedentary people and those who exercise regularly.

In addition to affecting the way your brain functions in general, sedentary behavior also alters your brain chemistry. In an August 2018 study published in the ​International Journal of Behavioral Nutrition and Physical Activity​, being sedentary for more than three hours a day was associated with an increased risk of experiencing depressive symptoms.

And in a September 2018 study published in ​Preventive Medicine Reports​, researchers found that even in healthy adults, changes to sedentary behavior strongly predicted changes in mental wellbeing — with increased sedentary behavior being associated with decreased mental health.

You might associated high-impact workouts or contact sports with an increased risk of bone and joint injuries, but as long as you play it smart, the opposite is actually true.

"Weight-bearing exercise has been shown to help stave off osteopenia and osteoporosis," Dr. Morski says. "And maintaining flexibility can help prevent injuries from falls and keep individuals able to perform daily activities much longer."

In a January 2018 study in ​Rambam Maimonides Medical Journal​, researchers found that parts of the body subjected to weight-bearing exercises had a reduction in bone mass loss and increased bone stiffness, which are changes that act as a barrier to the development of osteoporosis.

You likely already intuitively know this, but sitting on your couch and binging Netflix and chips isn't doing your midsection any favors. A 2017 May study published in the ​International Journal of Obesity​ linked sedentary behavior with both increased waist circumference and cardiovascular disease risk. On average, the more sedentary behavior one exhibits, the larger their waistline will likely be.

That's partly due to the fact that living a sedentary lifestyle decreases the total calories you burn. Consistently burning fewer calories can cause weight gain, and also increases your chances of developing insulin resistance — a condition that causes high blood sugar levels — which can lead to and predict cardiovascular disease, according to a August 2018 study published in ​Cardiovascular Diabetology​.

While researchers haven't figured out all the ins and outs of cancer and its risk factors yet, one thing is becoming increasingly clear: If you don't exercise, your risk of certain types of cancer increases.

Cancer — currently the second-leading cause of death in the world, according to a September 2018 report published by the World Health Organization — is caused by changes to DNA within cells (also known as gene mutations). In a December 2017 review published in ​Sedentary Behaviour Epidemiology​, researchers observed a link between being sedentary and an increased risk of several cancer types.

Based on the findings of 25 studies that looked at 17 cancer types, sedentary behavior was associated with an increased incidence of endometrial and ovarian cancers and potentially also breast, colorectal and lung cancers.

Conversely, regular exercise appears to be associated with a decreased risk of cancer. In a June 2019 study published in ​Medicine & Science in Sports & Exercise​, which involved several million study participants, researchers found a strong connection between more physical activity and a decreased risk for several types of cancer.

To ensure you don't increase your risk of experiencing the negative effects of a sedentary lifestyle, it's important to stay physically active.

According to the U.S Department of Health and Human Services (HHS), adults should engage in at least 150 minutes of moderate-intensity exercise per week, or 75 minutes of vigorous cardio. And they should aim for two full-body, weight-bearing, muscle-strengthening sessions a week.

The type of exercise that's best for you depends on factors such as your age, injury history and any health conditions you have. Personal preferences are also important to consider, as consistency is important when it comes to reaping the benefits of exercise. Whether you choose to walk, run, lift weights, swim, play basketball or combine different types of exercise, your priority should be focused on regular physical activity.