Why must an endotherm eat more food than an ectotherm of the same size?

Endotherms, or warm-blooded animals, maintain a constant body temperature regardless of the environment, which requires significant energy expenditure for thermoregulation. In contrast, ectotherms, or cold-blooded animals, rely on external heat sources to regulate their body temperature, leading to lower metabolic rates. Consequently, endotherms must consume more food to meet their higher energy demands for maintaining body heat and supporting metabolic processes. This increased food intake is necessary to sustain their active lifestyles and physiological functions compared to ectotherms of the same size.