Fat Burning Metabolism and Energy Systems 2 — Questions and Answers
Question 1: What respiratory quotient (RQ) value indicates the body is primarily burning fat for fuel?
- 1.0
- 0.85
- 0.70 (Correct answer)
- 0.55
Correct answer: 0.70
An RQ near 0.70 indicates fat is the primary substrate being oxidized; pure carbohydrate metabolism produces an RQ of 1.0.
Question 2: Approximately how many calories must be burned or restricted to lose one pound of body fat?
- 1,750 calories
- 2,500 calories
- 3,500 calories (Correct answer)
- 5,000 calories
Correct answer: 3,500 calories
One pound of stored body fat contains approximately 3,500 calories, so a total deficit of 3,500 calories — typically 500 calories per day over a week — is needed to lose one pound.
Question 3: Which energy system dominates during prolonged low-to-moderate intensity exercise lasting over 30 minutes?
- ATP-PC (phosphocreatine) system
- Anaerobic glycolysis
- Aerobic oxidative system (Correct answer)
- Lactic acid system
Correct answer: Aerobic oxidative system
The aerobic oxidative system dominates during prolonged low-to-moderate exercise, using oxygen to oxidize fats and carbohydrates for sustained ATP production.
Question 4: What happens to fat utilization as exercise intensity increases toward maximum effort?
- Fat utilization increases sharply
- Fat utilization decreases as carbohydrates take over (Correct answer)
- Fat utilization remains constant
- Fat becomes the only fuel source
Correct answer: Fat utilization decreases as carbohydrates take over
As intensity rises, the body shifts toward carbohydrate metabolism because glycolysis produces ATP much faster than fat oxidation can, meeting the higher energy demand.
Question 5: What is 'metabolic flexibility'?
- The ability to exercise at varying intensities
- The capacity to switch efficiently between burning fat and carbohydrates based on availability (Correct answer)
- The rate at which muscles grow after training
- The ability of metabolic enzymes to function at different temperatures
Correct answer: The capacity to switch efficiently between burning fat and carbohydrates based on availability
Metabolic flexibility is the body's ability to efficiently switch between fat and carbohydrate oxidation based on fuel availability and energy demands, a hallmark of good metabolic health.
Question 6: Which of the following best promotes fat oxidation during exercise?
- Consuming a large carbohydrate meal 30 minutes before exercise
- Exercising in a fasted state (Correct answer)
- Taking insulin prior to exercise
- Reducing total exercise duration
Correct answer: Exercising in a fasted state
Exercising in a fasted state lowers insulin levels and reduces glycogen availability, signaling the body to rely more heavily on fat oxidation for energy.
Question 7: Which tissue contributes most to resting energy expenditure due to its high metabolic activity?
- Adipose tissue
- Bone tissue
- Skeletal muscle (Correct answer)
- Connective tissue
Correct answer: Skeletal muscle
Skeletal muscle is highly metabolically active and burns significantly more calories per kilogram at rest than adipose tissue, making it critical to overall energy expenditure and fat loss.
Fat Burning Metabolism and Energy Systems 2
What respiratory quotient (RQ) value indicates the body is primarily burning fat for fuel?