Leptin

Specialist

also satiety hormone

What it isLeptin is a hormone manufactured and released by fat cells in proportion to total body fat mass. It travels to the hypothalamus where it signals "enough fuel on board."

DoesRegulates appetite, energy expenditure, thyroid output, and reproductive hormone production. The brain reads leptin as a long-term fat-stores gauge.

GoodLow-to-moderate leptin in a lean person reflects appropriate fat mass and a brain that's hearing the signal cleanly.

BadChronically high leptin causes leptin resistance — the brain stops listening, appetite stays elevated, and the metabolic state of obesity locks in. High leptin tracks visceral fat, insulin resistance, and cardiovascular risk.

Standard

Men 0.5–13.8 ng/mL; women 1.1–27.5 ng/mL.

Optimal

1–4 ng/mL men, 3–8 ng/mL women (lower is good)

Modifiers

Tracks body fat percentage; rises with sleep deprivation and overfeeding; falls during fasting and weight loss; women run higher than men.

How to optimize

Lifestyle: Sleep 7–9 hours — short sleep disrupts leptin signaling acutely. Resistance training to build muscle and shed visceral fat. Zone 2 cardio. Cold exposure may improve signaling.
Diet: Whole-food eating that drops body fat. Cut ultra-processed food, fructose, and seed oils — they appear to drive leptin resistance independent of calories. Time-restricted eating helps reset signaling.
Supplements: Omega-3 EPA+DHA (2–3g/day), berberine (500mg 3×/day), magnesium glycinate (300mg/day).
Peptides: GLP-1 agonists (semaglutide, tirzepatide, retatrutide) drive sustained leptin reduction through fat loss; MOTS-c improves metabolic signaling.
Drugs: GLP-1 agonists, metformin.

within Blood Sugar & Metabolic