Question

Basal metabolic rate is most closely associated with?

• A. Lean body mass
• B. Body surface area
• C. Daily activity
• D. Food intake

Hint:

Metabolically active tissue burns the fuel, fat is largely inert.

Answer 1

The Correct Option is A

Step 1: Basal metabolic rate (BMR) is the energy expended by the body at complete rest, in a neutrally temperate environment and in the post-absorptive state (about 12 hours after the last meal, with an inactive digestive system).
Step 2: Because BMR is measured at rest and after fasting, daily activity (option C) and food intake (option D) are excluded by definition, as they add energy expenditure above the basal level.
Step 3: BMR was classically expressed per unit of body surface area, but the metabolically active component of the body is the lean (fat-free) mass. Adipose tissue is relatively inert metabolically.
Step 4: If two people have the same surface area but different lean body mass, the one with greater lean mass has the higher BMR, since BMR scales with metabolically active tissue \(\left(\text{BMR} \propto \text{body weight}^{0.75}\right)\).
Conclusion: BMR is most closely associated with lean body mass, so option A is correct.