Anabolic hormone

An anabolic hormone is one that promotes building: taking smaller molecules and assembling them into tissue. The main ones are testosterone, insulin, growth hormone and IGF-1, with oestrogen playing important building roles too, particularly in bone.

Each does something distinct despite the shared label. Testosterone increases muscle protein synthesis and satellite cell activity. Insulin drives nutrients into cells and suppresses breakdown. Growth hormone acts largely through IGF-1, produced by the liver in response to it and locally in muscle in response to loading.

The reason to understand the category is to see through the marketing built on it. Training does produce short lived rises in testosterone and growth hormone, and for two decades those spikes were assumed to drive growth. Research since has found that the acute hormonal response to a session correlates poorly with the muscle actually gained, which undercuts programme designs built around maximising it.

What does predict growth is mechanical tension, weekly hard sets and enough protein and energy. The hormonal environment matters at the level of having a normal one, not at the level of nudging it for twenty minutes after training.

That distinction also explains the gulf between physiological and pharmacological. Supraphysiological anabolic steroid doses build muscle dramatically, which is precisely why they are controlled substances with serious consequences, and it says nothing about whether a supplement that nudges testosterone within the normal range would do anything at all. The evidence says it would not.

The everyday levers are the boring ones and they work by keeping the system normal rather than by boosting it: sleeping properly, not drinking heavily, keeping visceral fat in check, eating enough, and not training in a chronic deficit.

In practice, ignore anything sold on hormone optimisation and put the effort into training volume, protein and sleep, which is where the effect sizes actually are.