Catabolic hormone

A catabolic hormone promotes breaking down: mobilising stored energy and, where necessary, dismantling tissue to supply it. The main ones are cortisol, glucagon, adrenaline and noradrenaline, with thyroid hormones raising the overall metabolic rate at which all of it happens.

The label sounds hostile and is not. These hormones are how you access your own energy stores, which is required every night you sleep, every time you skip a meal and every time you sprint for a bus. A body unable to run catabolic processes would not survive a day.

Their pairing with anabolic hormones is the useful frame. Building and breaking down happen simultaneously and continuously, and what matters is the balance over days and weeks rather than the state at any moment.

Cortisol is the one most often demonised in fitness content. It rises normally with exercise, peaks in the morning by design, and the concern is chronic elevation from unrelenting stress, short sleep or training you are not recovering from, not the ordinary post-session rise that anti-catabolic products are sold against.

The genuinely useful application is understanding under-recovery. Sustained catabolic dominance shows up as stalled progress, poor sleep, raised resting heart rate, suppressed heart rate variability and a shorter temper, and the fix is load management, sleep and food rather than a supplement.

Muscle loss during dieting is the specific risk people are worried about, and it is addressed by adequate protein and continued resistance training, both of which have far better evidence than anything marketed as anti-catabolic.

In practice, treat these hormones as normal machinery, and treat a persistent imbalance as a signal to train less, sleep more or eat more rather than to buy something.