Human cells run on about 20‑30 % of the chemical energy we ingest, so a 70‑kg person produces roughly 1.5×10⁶ J each day just from metabolism—about 50 kW of sustained power over 24 hours. Compare that to deuterium‑tritium fusion: 1 kg of fuel releases around 3.5×10¹⁴ J, meaning 100 000 MW if you could keep it running continuously. In plain terms, fusion is millions of times more energetic per unit mass than your own body. But turning that into a portable, safe source is a whole other challenge—your metabolism is a biological battery, fusion is a physics engine. If you want to beat your own efficiency, you’re looking at a reactor the size of a town, not a protein shake.