The evolutionary logic behind growth hormone surges during food scarcity.
What the evidence says
- *On Nørrelund's review*, the evolutionary rationale is that preserving muscle during food scarcity was survival-critical[1]
- *The review's framing*: GH promotes fat oxidation as the primary fuel source, acting as a master fuel switch from carbohydrate and protein toward lipid utilisation[1]
- GH reduces protein catabolism via stimulation of lipolysis; FFAs are the actual protein-sparing agents[1]
- Without GH during fasting, protein loss increases by approximately 50% — *this figure reaches the library through papers citing the review, not from the review itself; see below*[1]
- The combination allows surviving temporary food shortage without losing hunting/gathering capacity[1]