Katabol

Katabol, often used as a shorthand for catabolic processes, denotes the set of metabolic reactions that break down complex molecules into simpler ones and, in doing so, release energy. The term derives from Greek katabole, meaning a throwing downward, reflecting the decomposition of macromolecules into usable components.

In biology, catabolism includes glycolysis, proteolysis, beta-oxidation, and the citric acid cycle, which feed into oxidative phosphorylation to generate ATP. Although many catabolic reactions are aerobic, others operate under anaerobic conditions, such as fermentation, producing energy with different yields.

Catabolic pathways are tightly regulated by enzymes and hormonal signals, notably glucagon, adrenaline, and cortisol, and by cellular energy status (the ATP/ADP/AMP ratio). They provide substrates during fasting, exercise, or stress and supply building blocks for repair when needed, balancing anabolic processes.

In health and disease, dysregulation of katabolic activity can contribute to muscle wasting (cachexia) or reduced energy availability, while excessive suppression of catabolism can impair mobilization of energy stores. The term is commonly contrasted with anabolic metabolism, which builds up biomolecules.