Why is there an energy loss at higher trophic levels of the food chain?

A trophic level is merely feeding level. The recurrent loss of energy due to metabolic activity puts limits on how much energy is available at higher trophic levels. Typically, it is the nutrient supply to the primary producers which ultimately controls how ecosystems function. If the nutrient supply grows, the result is an increase in production of autotrophs. All the other trophic levels will respond to the increased availability of food.

Energy is lost at every trophic level because trophic levels lose power due to several inefficiencies in the system. By reducing the food chain, there is less energy and biomass lost from one trophic level to the next. The lifestyle at each trophic level in an ecosystem has specific features which affect the efficiency of transfer of energy.

Each trophic level contains organisms that work through the food, chain by chain. Energy decreases as it moves up through trophic systems because energy is lost as metabolic heat when the organisms from one trophic level are consumed by organisms from the next level.

Only 10% of food is passed to the next chain in the trophic system and therefore to flesh, the rest in transmission is lost to insufficient digestion, respiration. The losses are high in mammals and birds because of high body temperature.