Why lipostatic set point systems are unlikely to evolve

Area of Science:

• Evolutionary biology
• Mathematical modeling
• Physiology

Background:

• Body fatness is often assumed to be regulated by a lipostatic set-point system.
• This system is thought to have evolved due to trade-offs between starvation risk and predation.
• Alternative models for body fat regulation exist.

Purpose of the Study:

• To evaluate the likelihood of set-point systems evolving compared to alternative models using mathematical modeling.
• To investigate the impact of parameter variability on the evolution of body fat regulation.

Main Methods:

• A mathematical model was developed to simulate mortality risks and identify optimal fatness levels.
• Markov Chain Monte Carlo (MCMC) simulations and Bayesian inference using Gibbs Sampling (BUGS) were employed.
• Error propagation from model parameters to optimal fatness levels was analyzed.

Main Results:

• Small variations (1%) in model parameters led to significant magnification (20-90%) in the optimal fatness level.
• A set-point centered on the mathematical optimum would only be correct on less than 8% of occasions.
• Parameter variability makes set-point regulation of body fatness highly improbable.

Conclusions:

• Set-point regulation of body fatness is unlikely to evolve given realistic parameter variations in mortality risks.
• A dual-intervention point system is a more plausible evolutionary model for body fat regulation.
• These findings have significant implications for interpreting molecular research on adiposity regulation.