Final answer:
True, total energy expenditure decreases in response to weight loss, mainly due to a reduction in thermogenesis, because the body lowers the basal metabolic rate to conserve energy.
Step-by-step explanation:
It is true that total energy expenditure is reduced in response to weight loss, and a significant component of that reduction is due to a decrease in thermogenesis. When a person reduces their calorie intake, their body, seeking to maintain homeostasis, may lower its basal metabolic rate (BMR) as a way to conserve energy. The BMR is the rate of energy expenditure by the body at rest, and it plays a crucial role in overall energy use. As a person loses weight, their BMR typically decreases, which means they burn fewer calories at rest. Furthermore, the efficiency with which the body converts internal energy to work is quite low, and therefore, more energy is lost than the work done, contributing to weight loss when exercising. However, as BMR decreases, the rate of weight loss may slow down, necessitating changes in diet and exercise to continue losing weight.