Post 2 · The five stations, and the one that decides everything

Fat doesn't just get oxidised. It goes through a production line, and every station is regulated.

① Mobilise. Triglyceride in the fat cell is split into fatty acids. Insulin brakes it; adrenaline accelerates it. (Glucagon's role here is smaller and far more contested than it's usually made out to be; more on that in Post 9.)

② Transport. Fatty acids aren't water-soluble, so they ride through the blood bound to albumin. Fat from around your organs drains into the portal vein and hits the liver before anything else sees it.

③ The gate. A long-chain fatty acid physically cannot enter the mitochondrion on its own. It has to be handed through by an enzyme called CPT1. This is the narrowest point in the entire line.

④ β-oxidation. Inside, it's cut two carbons at a time.

⑤ Disposal. The pieces enter the Krebs cycle and become ATP. Or, if there's a surplus, ketones.

Here's the part worth sitting with.

Almost everything the fitness industry sells you targets station ①.

Fat-loss pills. Stimulants. Cold plunges. Fasted cardio protocols.

All of them push harder on the station that was never the problem.

Fat mobilised with no deficit to oxidise it goes back to the store. (R§23)

Which of these five had you actually heard of before?

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Post 2 · The five stations, and the one that decides everything