Final answer:
When losing weight, the human body decreases its basal metabolic rate (BMR) in response to reduced caloric intake or increased energy demand. Exercise can raise the metabolic rate and improve weight loss, while the body's inefficiency in converting energy to work also helps in losing weight.
Step-by-step explanation:
When losing weight, the human body naturally adjusts its basal metabolic rate (BMR). As either energy demand rises or caloric intake decreases, the body responds by decreasing the BMR to conserve energy instead of eliminating its own fat to replace lost food intake. This adjustment can make you feel less energetic and you might experience feeling cold more easily. Nonetheless, to effectively lose weight, it is essential to ensure that the number of calories burned exceeds the number of calories ingested.
Exercise is beneficial for weight loss because it not only leads to heat transfer and work done by the body but also raises the metabolic rate even at rest. This increase can help counter the body's natural tendency to lower the BMR when the calorie intake decreases. In addition, bodies are relatively inefficient at converting internal energy to work, meaning a larger amount of internal energy is expended than the actual work done.