2,4-dinitrophenol (DNP) is a FDA-banned weight-loss agent and EPA-regulated environmental toxicant, traditionally used in research labs as an uncoupler of OXPHOS. Although not licensed for human consumption, DNP and DNP crystal form are used by bodybuilders and extreme dieters for their fat burning properties through inhibiting efficient energy (ATP) production in cells. Through uncoupling mitochondrial oxidative phosphorylation by facilitating proton transport across the mitochondrial membrane, DNP leads to rapid consumption of energy without generating ATP and consequently, to increased fat metabolism. However, the weight-loss effect comes with serious, and in some cases potentially fatal, adverse side effects, namely hyperthermia (the leading cause of fatality with acute DNP toxicity) and cardiac arrest, but also diaphoresis, tachycardia, tachypnea, skin toxicity, Fourier’s gangrene and cataracts with low dose chronic exposure. The proposed mechanism of DNP induced toxicity suggests the activation of ATP-sensitive K channels.