The energy pyramid is broader at the base because it illustrates the concept of energy flow in an ecosystem. Energy is highest at the base of the pyramid, where the primary producers are located, and it decreases as you move up the trophic levels. This decrease in energy happens because as organisms consume food, not all of the energy is transferred to the next level. A portion of it is used by the organism itself for metabolic processes, and some is lost as heat. This loss of energy is why fewer organisms exist at the higher trophic levels, leading to the pyramid's shape.