leptin from adipose

Leptin from adipose tissue is the body’s “fuel gauge” reported to the brain. Fat cells release leptin in proportion to how much fat they hold, so the more fat you carry, the more leptin circulates — telling the brain that energy stores are full and it is safe to eat less.

Made by adipocytes, leptin travels to the hypothalamus and acts on appetite circuits to reduce hunger and modestly raise energy expenditure. It is the prototype adipokine — the discovery that fat tissue secretes a hormone reporting its own mass was a turning point that reframed fat as an endocrine organ. Leptin also signals long-term energy sufficiency to systems such as reproduction; when fat (and leptin) drop too low, fertility can shut down to conserve resources.

An important caveat resolves a common confusion: people with obesity usually have high, not low, leptin. The problem is leptin resistance — the brain stops responding properly to the signal — so simply giving more leptin does not treat common obesity. Leptin replacement is, however, life-changing for the rare individuals who cannot make leptin at all (congenital leptin deficiency).