In the RER formula, what exponent is applied to body weight?

In the RER formula, what exponent is applied to body weight?

• A. 0.25
• B. 0.5
• C. 0.75
• D. 1.0

Answer: (C)

Metabolic rate scales with body size in a non-linear way, so the resting energy needs are not simply proportional to weight. The standard resting energy requirement uses body weight raised to the three-quarters power, a reflection of allometric scaling (Kleiber’s law). This means the exponent applied to body weight is 0.75, giving the commonly used formula RER = 70 × BW^0.75 (with BW in kilograms). Using 0.75 fits the observed scaling of metabolic rate across different animal sizes, whereas 1.0 would imply direct proportionality to weight, and 0.25 or 0.5 would not align with the typical veterinary nutrition model.

Metabolic rate scales with body size in a non-linear way, so the resting energy needs are not simply proportional to weight. The standard resting energy requirement uses body weight raised to the three-quarters power, a reflection of allometric scaling (Kleiber’s law). This means the exponent applied to body weight is 0.75, giving the commonly used formula RER = 70 × BW^0.75 (with BW in kilograms). Using 0.75 fits the observed scaling of metabolic rate across different animal sizes, whereas 1.0 would imply direct proportionality to weight, and 0.25 or 0.5 would not align with the typical veterinary nutrition model.