Leptin is a hormone produced by adipose tissue that signals satiety to the hypothalamus. In a healthy state, rising leptin after meals suppresses appetite and increases energy expenditure. However, in obesity, chronically elevated leptin leads to leptin resistance — the brain stops responding to the signal, creating a vicious cycle of increased appetite despite high leptin.

Leptin resistance is now considered a key driver of obesity, similar to how insulin resistance drives type 2 diabetes. High leptin with high BMI suggests leptin resistance, while low leptin with normal BMI is appropriate.

Leptin also has pro-inflammatory and pro-thrombotic effects at high levels, contributing to the cardiovascular risk associated with obesity. Weight loss, adequate sleep, and reducing dietary fructose can help restore leptin sensitivity.

What It Measures

Serum leptin concentration reflecting adipose tissue mass and metabolic signaling to the brain.

Reference Ranges

How GATOR Tracks This

Related Biomarkers