I recently started to drastically reduce the amount of sugar i took in a day and drank mostly water and take multivitamin and i have more energy. why?

Depends on diet: Many people report increased energy from lower carbohydrate diets. It depends on many factors including your health, medicines, sleep habits, hormonal factors, immunity, etc. Sugar consumption often gives people a quick burst of energy but then they get the "sugar crash". Less sugars allow the body to more smoothly create energy as it is needed rather than having the Insulin spikes from hi suga.