Yes fasting does help you increase your energy.
Fasting causes your body to turn to existing excess fat reserves as a source of energy in your body and your energy levels will increase as a result and you'll lose weight as well.
Fasting also makes your metabolism work a lot more efficiently which in turn helps to increase your energy.
You may not have as much energy at the time you're fasting but if you fast often enough then eventually your metabolism will begin to work much better.
When the bodies metabolism is working better then you can have an increase in energy.
Also if you want to make sure you have enough energy be sure to eat a healthy diet of fruits and vegetables and get plenty of sleep at night.