Glucose, a simple sugar, is the brain's primary fuel...
If you don't have enough in you, you can potentially start to make bad decisions and inaccurate assessments of how well your body is performing, which leads to overextending oneself and possibly fainting or falling into shock. To help prevent fainting, some piercers have cookies available to their clients.
To maintain blood glucose levels, eating sugary food helps. However, be aware that eating too much sugary food carries the risk of inducing Type-2 diabetes. Diabetics should take care to monitor their blood-sugar levels.