It can cause damage to various organs in your body as follows:
Heart
When you sit for long periods of time, your blood flows more slowly and your muscles burn less fat, which makes it easier for fatty acids to clog your heart. Research published in the Journal of the American College of Cardiology showed that women who sit for 10 or more hours a day may have a significantly greater risk of developing heart disease than those who sit for five hours or less.
Pancreas
Your body’s ability to respond to insulin will be affected after just one day of excess sitting, which leads your pancreas to produce increased amounts and may lead to diabetes. Research published in Diabetologia found that those who sat for the longest periods of time were twice as likely to have diabetes or heart disease, compared to those who sat for less than six hours. Sitting for more than eight hours a day has also been associated with a 90% increased risk of type 2 diabetes.
Colon, lungs, uterus
Excess sitting may increase your risk of colon, breast and endometrial cancers. The mechanism isn’t known for certain, but it could be due to excess insulin production, which encourages cell growth. It could also be caused by the fact that regular movement boosts antioxidants in your body that may eliminate potentially cancer-causing free radicals.
Findings presented at the 2015 Inaugural Active Working Summit also found that sitting increases the chance of various types of cancer as follows:
- Lung cancer by 54%
- Uterine cancer by 66%
- Colon cancer by 30%
Digestion
Sitting down after you’ve eaten causes your abdominal contents to compress, slowing down digestion. This, in turn, can lead to cramping, bloating, heartburn and constipation, as well as to conditions caused by microbial imbalances in your body, which are associated with the pathogenesis of both large and small intestine disorders. Intestinal disorders include inflammatory bowel disease, irritable bowel syndrome (IBS), etc.
Brain
Your brain function slows when your body is sedentary for too long. Your brain will get less fresh blood and oxygen, which are needed to trigger the release of brain- and mood-enhancing chemicals.