can you tell me clearly what energy balanced means?

Question

of food not physics

Answer 1

your reserves of energy equal your output of exertion.

Answer 2

In an open system, energy into that system must equal energy coming out of that system if the energy is in balance. For example, your car's engine is an open system...an open system is simple one that has input and output from and to outside the system.

Input to your car's engine includes gasoline, electricity, and air, which, when mixed and ignited, create the propulsive energy of that engine. The output from that engine, which is in balance with the energy input by the gasoline (petrol), electricity, and air, is the propulsive energy plus loses of energy in heat, water vapor, and exhaust fumes.

One could write a balanced equation of sorts: Input Energy = Gas + Air + Electricity = Kinetic Energy (KE) + Heat + H2O + Exhaust = Output Energy; where the kinetic energy is the propulsive energy for your car. Note, you can write KE / (Gas + Air + Electricity) = efficiency; which would tell you how efficient the car engine was in getting useful output (the KE).