BMR, MMR, BMI, WTF?

-or-Breaking Kleiber’s Law

How do we determine an accurate Basal Metabolic Rate?

■ Accounts for 60-70% of calories used per day.

■ Impacts longevity.

■ Optimal feeding for patients with disease states.

■ Athletic performance.

Conflicting TheoriesAllometric Cascade Theory

BMR = MR0ΣC1(M/M0)

Kleiber’s Law

q0 ~ 73.3*M¾

Kleiber, M. 1961. The Fire of Life. Wiley. 454 p. Hochachka, P., et al. 2003. Allometric cascade: a model for resolving body mass effects on metabolism. Nature.doi:10.1016/S1095-6433(02)00364-1

Strengths of Kleiber’s Law1 2

3

♀ = 1500 ♂ = 1700 = 150

Works across a wide range of species Easy to calculate

Pretty close to what we already believe

Weaknesses of Kleiber’s Law

21

Doesn’t work well with creatures rapidly growing

Struggles to be accurate across a single species

Strengths of Allometric Cascade Theory1

3

♂ = 1603 = 153

2

Super accurate Works well with creatures growing

Even closer to what we believe

Weaknesses of Allometric Cascade Theory1

2

Bad Math

Really complicated

Allometric Cascade Theory is Better Than

What we Have■ Easy enough to generalize for humans.

■ WAY better than Harris Benedict.

■ Can take into account variables such as disease states.

■ Scalable from bacteria to blue whales.

■ Easily modified to take into consideration periods of growth.