There is no question that human body needs energy which could be kind of fuel of the whole function of each part of the human body. People could get the energy from two things after all. When people are getting too tired because of many kinds of activities, it means that they are running out of energy. And they should sleep properly for a while and they could restore their energy back. But, people must not forget that food is the most important source of energy after all.
When people do not eat properly with many kinds of food which could be the source of energy, they could find out that their body will not run properly. The clearest view that people could see is that it seems like they do not have enough power to do their activity. So, it is really important to fulfill the energy need of body with the right food.
People of course have to understand about what kind of food which could be replaced as energy inside the body. Food which consists of carbohydrates and fats is the greatest resource of energy after all.
People have to remember that they have to consume balance food including for food which could provide them with energy.