hormone
Leptin
Leptin is a hormone made mainly by adipose tissue that signals information about stored energy to the brain.
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Leptin receptors in the hypothalamus participate in appetite and energy-homeostasis circuits; circulating concentrations also vary with body fat and other context.
How it works
An energy-store signal
Fat cells release leptin in relation to stored energy. It acts through receptors in the brain, especially in the hypothalamus, contributing to appetite and other hormonal responses.
Roles and processes
Leptin signals to Appetite regulation
Leptin is one peripheral signal integrated by appetite-regulation circuits.
Evidence: Established · Source checked 2026-09-05 · Sources: NIH National Library of Medicine: Physiology, Appetite And Weight Regulation; NIH National Library of Medicine: Physiology, Leptin
Worth knowing
More leptin does not mean a linear effect. Circulating leptin reflects adipose stores but is also shaped by energy state, inflammation and other signals.
A closer look
Receptor signalling shapes response
Leptin signalling involves JAK–STAT and other intracellular pathways, so the response depends on receptor signalling as well as circulating concentration.
Two appetite pathways receive the signal
In the arcuate nucleus, leptin activates neurons linked with reduced food-seeking signals (proopiomelanocortin, POMC) and inhibits neurons linked with hunger signals (agouti-related peptide and neuropeptide Y, AgRP/NPY).
References
Source-checked local draft.
Human editorial review pending.