A recent analytical paper by Arencibia-Albite demonstrates that the energy balance model (EBM) is internally inconsistent. The proof does not rely on any empirical dataset. The argument is that EBM’s own equations require energy balance and body weight stability to be simultaneous equilibrium states. That equilibrium requires stable fat mass and fat-free mass. Stable fat-free mass requires nitrogen balance. Nitrogen balance is impossible given obligatory nitrogen losses. The model cannot simultaneously satisfy its own equilibrium conditions. This commentary explains the proof for a general nutrition science audience, situates it within the broader critique of the energy balance framework, and discusses its implications for research and practice. The proof is analytical, not empirical. It shows that the model’s equations do not close. This does not mean that energy is irrelevant. It means that energy balance alone cannot describe body weight regulation. Mass balance offers a more complete description. The clinical implication is direct: when patients fail to lose weight despite adherence to caloric restriction, the failure may lie in the framework, not in the patient.