Insulin spikes

University of Colorado at Denver human physiologist Audrey Bergouignan explained that sitting too much can mess with your insulin production, reports the Washington Post. This can put you at greater risk for diabetes. Double whammy: Sitting could be bad for your mind, too. An April 2012 study in the Annals of Behavioral Medicine analyzed the association between sedentary behavior and mental well-being using Well@Work, a workplace health promotion project in the UK.

According to self-reported survey data from almost 3,500 people of non-occupational sitting time — watching TV, using a computer, driving, etc. — sitting time outside of work was negatively associated with mental health for women. Again, men got off comparatively easy — only sitting time at the computer negatively impacted their mental well-being.

Slowed brain function

Newcastle University professor of movement and metabolism Mike Trenell told the Daily Mail that without movement, muscles pump less fresh blood and oxygen through your brain. By reducing “excessive sitting” to less than three hours a day, the U.S. life expectancy could increase by two years, according to a July 2012 study in BMJ Open. Reducing TV time to less than two hours a day would bump it up by 1.4 years.

(By comparison, smoking knocks off 2.5 years of life expectancy for men and 1.8 years for women.) The study estimated that the average adult spends 55 percent of his or her day doing something sedentary, but also notes that even high levels of self-reported sitting could be conservative. It’s not easy to remember all the time you’ve spent sitting during the day, since it’s not necessarily a domain-specific behavior like watching TV.

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Weak bones

PreventDisease.com explained that excessive sitting can lead to osteoporosis, citing a 2010 study published in The National Center for Biotechnology Information. Obese individuals sit 2.5 more hours a day than lean individuals, according to a November 2009 Obesity study. In turn, sitting more is associated with Metabolic Syndrome, a combination of factors — like abdominal obesity, low levels of “good cholesterol,” high blood pressure, high triglyceride levels or hyperglycemia — that together put you at a higher risk for serious medical issues like heart disease, stroke and diabetes.

A review study in PLOS ONE last year confirmed that people who spent more time being sedentary were 73 percent more likely to have metabolic syndrome. In 2005, a group of researchers theorized that reducing TV and computer use to less than one hour a day outside of work could reduce the prevalence of adult metabolic syndrome in the U.S. by 30 to 35 percent.

Aches and pains

Inactivity might be the cause of your sore back. The Financial Times reports that when you slump in your seat, you can strain your back muscles. Even if you’ve been diagnosed with cancer, sitting could still be what kills you. A January 2013 study in the Journal of Clinical Oncology found that both before and after being diagnosed with colorectal cancer, more leisure time spent sitting down meant a higher risk of death.

The study tracked the self-reported habits of more than 2,000 patients with colorectal cancer for up to 16 years after their diagnosis. The most physically active had a 28 percent lower chance of dying than those who exercised less. Those who spent at least six leisure hours a day sitting had a 36 percent greater risk of dying than those who sat less than three hours a day.

Stiff spines

When you sit for too long, your soft discs between vertebrae become squashed, leading to inflexibility, according to a group of scientists interviewed by the Washington Post. A March 2012 study in the Archives of Internal Medicine tracking more than 200,000 Australian individuals 45 years and older found that regardless of sex, age and body mass, sitting puts you at a higher risk for mortality from all causes. People who sat more than 11 hours a day had a 40 percent higher risk of dying within three years. The risk of death was much lower for people who exercised five hours a week or more, but it didn’t negate the sitting death-trap. Time to shell out for a standing desk.

Heart disease

Mercola.com reported that women who sit for 10 more hours a day have a higher risk of heart disease , according to the Journal of the American College of Cardiology. An October 2012 analysis of a self-reported survey — 6,379 people between the ages of 40 and 75 — found that even controlling for physical activity and body mass index, those who sat less had lower risk of having chronic kidney disease. The effect was especially profound in women: When they cut down their sitting time from a full workday to only three hours, their risk fell by more than 30 percent. For men, the risk decreased by 15 percent.

Decreased hip mobility

Livestrong.com explains that sitting too much causes your hip muscles to shorten and tighten, limiting your range of motion.

Higher rates of cancer

Harvard Health Publications explained that separate studies have linked excessive sitting to higher rates of cancer and cancer-related deaths.

Feeble glutes

Unsurprisingly, sitting on your butt all day is bad for your butt.

Dan Giordano, cofounder of Bespoke Treatments Physical Therapy, told SELF that sitting all day causes your glutes to essentially “shut down.”