Definition of the word burn off

The expression "burn off" originated in the mid-19th century as a result of rural practices involving the clearing of land. In many agricultural areas, farmers would conduct controlled burns as a way to eliminate excess vegetation and prepare the soil for planting. This process, known as prescribed burning, would involve setting fire to the undergrowth and allowing it to spread until it consumed all the unwanted foliage. The concept of "burning off" gained wider usage as a metaphorical term, particularly in reference to excess fat or calories being removed through physical exertion. In this context, the phrase describes the process of reducing the body's stored energy through intensive exercise or activity, much as a controlled burn would consume unwanted vegetation.