STRUCTURAL THEORIES OF BASAL METABOLIC-RATE

Because cells and organisms interface with the environment through surfaces, their design should be governed by surface laws. Yet, basal metabolic rate is not proportional to the 0·67-power of body mass (surface law) but to the 0·75-power of body mass. From the many theories that have derived a surface law, Teissier's dimensional analysis theory was probably the neatest. However, the surface law has been empirically invalidated. Moreover, Teissier assumed that times in the prototype animal and a similar one with different size are in the same ratio as their linear sizes. This is incorrect, however, because heart rates, being inverses of times, should be proportional to the 1 3-power of body mass-but are proportional to the 1 4-power of body mass, which is consistent with a 0·75-power law of basal metabolic rate. McMahon's recent attempt to explain the deviation of the empirical law from a surface law based entirely on structural considerations, is critically examined. It does not appear that purely structural considerations could explain the deviation between the empirical 0·75-law of basal metabolic rate and the surface law. © 1979.