Dinitrophenol is an ionophoric compound that short circuits mitochondrial ATP production. This cessation of ATP production via the mitochondria leads to an increase in the metabolic rate (as substrate is utilized at a higher rate so cytosolic ATP can sustain life) and subsequent weight loss.
It is one of the few chemical compounds that is causatively linked to death. Overdosing on Dinitrophenol leads to toxicity via excessive heat production, irregular breathing and heartrate, and mitochondrial dysfunction.