Refined sugars put the body under great stress and and actually cause the body to consume itself in the effort to keep the brain alive. You can replace the sweetness by eating fruits like grapes that do not damage the body as refined sugar does. The second cause of low energy is a lack of good bacteria in the intestines. There are about 8 different bacteria that work in the small and large intestines. When good bacteria are destroyed, as they are by the use of antibiotics, by exposure to chlorinated water or by consuming preserved foods, the 4 vital functions of the good intestinal bacteria grind to a halt.
Food now sticks to the intestine wall.
Bad bacteria, molds, yeast and parasites now have an ideal environment in which to flourish. Toxic sludge builds up, which dumps poisons into the bloodstream along with whatever food the body manages to absorb. The third cause of low energy is the use of antibiotics without correcting the damage they cause. By destroying friendly bacteria, antibiotics set the stage for an infestation of molds and yeasts in the intestines and then the entire body. These molds and yeasts are normally kept in check by the friendly bacteria, and balance reigns in the body.