Leptin
The fullness signal. Leptin is produced by fat cells to tell your brain how much energy you have stored. High leptin should suppress appetite and boost metabolism. But leptin resistance—when the signal doesn't get through—is a major driver of obesity and metabolic dysfunction.
What Leptin Does (When Working)
Suppresses Appetite
Signals hypothalamus that energy stores are sufficient. Reduces hunger drive.
Boosts Metabolism
Increases energy expenditure. Supports thyroid function. Burns more calories.
Fat Burning
Promotes lipolysis. Favors fat oxidation over storage when adequate.
Reproductive Function
Signals adequate energy for reproduction. Low leptin = low fertility hormones.
Immune Function
Modulates immune response. Links nutrition status to immunity.
Bone Health
Affects bone metabolism. Complex effects on bone formation and resorption.
Leptin Resistance
The real problem isn't low leptin—obese individuals have HIGH leptin. The brain doesn't hear the signal:
What Causes It
Chronic high leptin, inflammation, high triglycerides blocking transport, hypothalamic inflammation.
What Happens
Brain thinks you're starving despite excess fat. Increases hunger, slows metabolism, promotes fat storage.
Vicious Cycle
More fat → more leptin → more resistance → more hunger → more fat. Hard to break.
Like Insulin Resistance
Same pattern as insulin resistance. Often occur together. Metabolic syndrome connection.
Improving Leptin Sensitivity
Reduce Inflammation
Omega-3s, reduce seed oils, whole foods. Inflammation blocks leptin signaling.
Lower Triglycerides
Triglycerides block leptin transport to brain. Reduce carbs, especially fructose.
Sleep
Sleep deprivation lowers leptin, raises ghrelin. Sleep is weight-regulating.
Avoid Snacking
Constant eating keeps leptin elevated. Time-restricted eating may help reset.