Firstly, it burns more calories. You're suddenly able to pace, dance, fidget, foot-tap and so on, as humans naturally do. This extra movement not only burns calories, but also allows the blood to circulate better. In fact, standing at work instead of sitting can burn 280 extra calories every single day, amounting to a significant 2,000 calories in a week - over a year, that amount of calories equates to a loss of 20 pounds in a year.
Standing also naturally improves your posture and strengthens muscles, allowing your body its natural movement and taking the pressure off your joints and your spine. The benefits, as well as best practices, of standing desks have been well documented. A great example is this e-book on standing desks
by specialist company, Updesk.
The sluggish, tired feeling created by sitting all day will suddenly disappear, meaning you feel more energised and productive throughout the day, with the increased blood flow making people vibrant and alert. Similarly, the increased blood flow is crucial for good digestion, so you will find you have much more energy after meals.