Final answer:
Your metabolism continues to work while you are at rest, known as basal metabolic rate (BMR). Exercise raises your metabolic rate even during rest periods, aiding weight loss. The body's metabolism adjusts to energy intake changes, and efficiency of converting energy to work affects energy expenditure.
Step-by-step explanation:
Your metabolism is working even when your body is at rest. This state of rest is scientifically known as the basal metabolic rate (BMR), which is the rate at which your body expends energy to maintain basic physiological functions while you are not active. The BMR accounts for most of the calories your body burns in a day, with the liver and spleen consuming the most energy, followed by the brain. Exercise can raise your metabolic rate even when you are at rest, contributing to weight loss. However, the body's response to periods of low energy intake, such as during dieting, can lead to a decrease in BMR, which might make subsequent weight loss efforts less effective.
The body's energy efficiency plays a role in how we lose weight. The conversion of internal energy to work during physical activities is relatively inefficient, meaning most of the internal energy expended by the body is lost as heat rather than as work done. This is one reason why exercise can lead to significant energy loss and help in weight loss, as the metabolic rate stays elevated even during periods of rest after the exercise.
It is important to note that living systems are not in thermal equilibrium. Daily fluctuations in energy intake and activity can significantly affect one's metabolic processes, including the rate at which the body stores or burns fat.