1. Harvard Medical School, Boston, Massachusetts 02115, USA
2. David Geffen School of Medicine at the University of California at Los Angeles, Los Angeles, California 90024, USA

Correspondence to: Walter Fontana¹ Correspondence and requests for materials should be addressed to W.F. (Email: walter@hms.harvard.edu).

For more than three-quarters of a century it has been assumed¹ that basal metabolic rate increases as body mass raised to some power p. However, there is no broad consensus regarding the value of p: whereas many studies have asserted that p is 3/4 (refs 1–4; ‘Kleiber’s law’), some have argued that it is 2/3 (refs 5–7), and others have found that it varies depending on factors like environment and taxonomy^{6, 8, 9, 10, 11, 12, 13, 14, 15, 16}. Here we show that the relationship between mass and metabolic rate has convex curvature on a logarithmic scale, and is therefore not a pure power law, even after accounting for body temperature. This finding has several consequences. First, it provides an explanation for the puzzling variability in estimates of p, settling a long-standing debate. Second, it constitutes a stringent test for theories of metabolic scaling. A widely debated model¹⁷ based on vascular system architecture fails this test, and we suggest modifications that could bring it into compliance with the observed curvature. Third, it raises the intriguing question of whether the scaling relation limits body size.

MORE ARTICLES LIKE THIS

These links to content published by NPG are automatically generated.