Leptin / leptin resistance
DELeptin / Leptinresistenz
Leptin is a hormone your white fat releases, in proportion to how much fat you carry. It acts on receptors in your hypothalamus (especially the arcuate nucleus) to curb appetite (via melanocortin signaling) and boost energy use. Think of it as your body's main long-term 'fat gauge'. Its levels follow a daily rhythm and respond quickly to insulin. Fasting or weight loss drops leptin; weight gain raises it over days to weeks. 'Leptin resistance' is when your brain stops responding properly to leptin, even though levels are normal or high. That keeps appetite high and energy use low. Proposed causes include poor leptin transport across the blood-brain barrier, fewer working receptors, and inflammation disrupting the JAK2/STAT3 signal (via molecules like SOCS3). Leptin resistance is present in most people with obesity. And it is tied to insulin resistance, metabolic syndrome, and the hard-to-fix leptin drop that follows weight loss.
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