Late night workers resort to drinking coffee to keep them awake. As natural substitute to coffee with a detoxifying effect is Japanese or Chinese green tea. The Japanese or Chinese green tea gives the same kick because it also contains caffeine but it does not contain substances that are irritating to the stomach.
Diet pills are also stimulants for the body to be kept alive. This may be observed among athletes specially, during time for competitions because they give more energy. They are being taken albeit the toxic effect in the body. In lieu of this, athletes must take fruits instead due to their natural detoxifying effects.
For cigarette smokers who think smoking stimulates their mind to think, they must think twice for smoking causes cancer. If they take carrots, they will experience the same effect in a more natural way.
For red meat lovers who really feel good and strong after feasting on said food, they better think about cutting on it. Fish is a better substitute.
Now, we understand why our parents keep on reminding us to eat fruits and vegetables. They give us energy in more natural ways plus they keep us fit and healthy.