Clipping two carbons at a time
Beta-oxidation is the repeating sequence that breaks fatty acids down for energy inside the mitochondrion. Each turn of the cycle runs through four enzymatic steps that remove a two-carbon unit from the fatty acid chain in the form of acetyl-CoA. Alongside that acetyl-CoA, each turn captures energy in the carriers NADH and FADH2, which later feed the electron transport chain to make ATP. A long-chain fatty acid is processed through many successive turns, progressively shortening until it is fully converted.
The acetyl-CoA produced typically enters the citric acid cycle for further energy extraction, linking fat breakdown to the same final pathway used by carbohydrate metabolism.
Why entry into the mitochondrion is the bottleneck
Beta-oxidation itself is efficient, but long-chain fatty acids cannot freely cross the inner mitochondrial membrane. They depend on the carnitine shuttle to get in, which makes that transport step a key control point for how fast fat can be burned. This is why carnitine availability and shuttle activity, rather than the cycle enzymes themselves, often feature in discussions of fat metabolism.
This is general educational information about a metabolic pathway, not medical or supplementation advice. Claims that boosting beta-oxidation directly causes fat loss oversimplify a process governed mainly by overall energy balance, so consult a qualified professional before acting on such claims.