Lots of sitting can slow down your metabolism, because you're not using large muscles (like your legs).
A 2010 study found that sitting for 23 hours or more per week increased the chances of developing heart disease by 64%.
See also: Sitting down is the new smoking. Here are three ways to quit
See also: How to stay healthy at work
he worst bit is that this is regardless of exercise, which doesn't necessarily offset the effects of sitting all day.
Sitting for long periods of time stalls processes that are important for breaking down fats and sugars in the body.
When you sit for too long, the discs in your back can become distorted, affecting tendons and ligaments around them.
Sitting hunched in a chair means your abs and glutes aren't being used, which can make them soft.
Slouching can also strain your neck and cause shoulder and back pain.
So what can you do to help?
If you have no choice but to sit, sit up straight with your feet flat on the floor and with lower back support.
Rest your elbows and arms on the chair or desk, with relaxed shoulders and hands at below elbow level.
Take breaks from sitting every hour to stand or go for a short walk.
Try doing some yoga poses once in a while, like cat-cow.
Stand up whenever you can: for example, when you take a phone call.
Even a little simple light stretching can help.