Final answer:
The body conserves energy during reduced caloric intake by lowering its basal metabolic rate (BMR), which can make a person feel colder and less energetic and can slow weight loss.
Step-by-step explanation:
In times of reduced kilocaloric intake, the body attempts to conserve energy and preserve body tissues by lowering its basal metabolic rate (BMR). The BMR is a measure of how quickly the body uses energy while at rest. To compensate for lower energy intake from food, the body decreases its metabolic rate. This reduction in metabolic rate can make a person feel colder and less energetic because the body is conserving energy, and it can also result in slower weight loss despite a caloric deficit.
Furthermore, the body's efficiency in converting internal energy to work is quite low, meaning more energy is lost than the work produced. This imbalance can further affect weight loss efforts. However, exercise can counteract these effects by increasing both heat transfer and the metabolic rate, aiding in weight loss.