The hibernation bridge: torpor and insulin resistance

Torpor and insulin resistance share one machine: the PDK4 fuel-sparing program. In torpor it is a REGULATED low-fuel attractor that returns after perturbation (True); run as a CHRONIC supra-spinodal misfire it becomes insulin resistance -- the state crosses to the low-disposal basin and stays (True). Same machinery, opposite regulatory status.

RD4, the package's namesake hypothesis. PDK4 (γ 1.4112) drives glucose sparing. The R19 distinction is regulatory: a defended low setpoint (torpor) versus a chronic crossing held in the disease basin (insulin resistance). Framing [V]; the PDK4 co-upregulation biology is [O] cited; absolute [O].

One machine, two fates

torpor = a REGULATED low-fuel attractor (returns after perturbation); insulin resistance = the SAME fuel-sparing program driven CHRONICALLY past the spinodal so the state crosses to and stays in the low-disposal (hyperglycemic) basin -- regulation lost.

Why this is a bridge, not a metaphor

The fuel-switch is the SAME gene with the SAME promoter read in both cases; what differs is whether the program is engaged as a defended, reversible state or as a chronic, supra-spinodal drive that crosses and sticks. That is a concrete, testable claim about regulatory status, not an analogy.

Grades and firewall

The R19 framing is [V]. The biological claim that PDK4 is co-upregulated in both torpor and insulin resistance is [O] CITED -- the model places the switch; it does not derive the regulatory program. This chapter is a hypothesis, not a clinical statement.