Question

The resting metabolic rate decreases in subjects that lose weight on a low-calorie diet. Which of the following factors are contributors to this weight loss-induced decline in resting metabolic rate?

a. a decrease in circulating thyroid hormone
b. reduced sympathetic nervous system activity
c. the loss of fat free mass
d. all of these contribute to the decrease in resting metabolic rate

Answer 1

The decrease in resting metabolic rate in subjects that lose weight on a low-calorie diet is primarily due to a decrease in circulating thyroid hormone, reduced sympathetic nervous system activity, and the loss of fat free mass.

Step-by-step explanation:

The decrease in resting metabolic rate in subjects that lose weight on a low-calorie diet is mainly due to three factors:

1. A decrease in circulating thyroid hormone: Thyroid hormone plays a crucial role in regulating metabolism. When weight is lost, the body produces less thyroid hormone, leading to a decrease in metabolic rate.
2. Reduced sympathetic nervous system activity: The sympathetic nervous system is responsible for increasing metabolic rate. Weight loss can decrease sympathetic activity, resulting in a decline in resting metabolic rate.
3. The loss of fat free mass: Fat-free mass, such as muscle, requires more energy to maintain compared to fat. When weight is lost, there is often a loss of fat-free mass, which contributes to the decline in resting metabolic rate.