Dinitrophenol causes weight loss by sharply increasing the metabolic rate, according to Wikipedia. The heightened metabolic rate causes the body to break down fat and carbohydrates at an increased pace. However, the use of DNP for dieting is prohibited by most national regulatory bodies, including the Food and Drug Administration and the United Kingdom's Food Standards Agency. For this reason, ingestion of DNP in any form should be avoided.
According to Wikipedia, DNP reduces the efficiency of the metabolic process. The body is therefore forced to break down larger-than-usual amounts of fat and carbohydrates to meet its normal energy needs. According to the Guardian, this process increases metabolism by up to 50 percent. Individuals using DNP can therefore lose a great deal of weight -- up to 1.5 kg a week, according to the Guardian -- without the need to vary diet. However, a serious side effects of increasing metabolism using DNP is elevated body temperatures. In a case reported by the Guardian, a man died after his body temperature reached 43.3 C, equivalent to 109.94 F. This problem was first noted by Maurice Tainter and Windsor Cutting of Stanford University, the first scientists to properly study the effects of the chemical on the human body. While appreciating its potential for helping individuals shed unnecessary weight, they also warned about its potentially fatal side effects. According to Wikipedia, the chemical was banned for human use in 1938.