SHBG (sex hormone-binding globulin)

A blood protein that binds and carries sex hormones. Obesity lowers it, which reduces measured total testosterone — a reason obesity can mimic low testosterone.

Updated Jul 16, 2026

SHBG (sex hormone-binding globulin) is a protein that binds and carries sex hormones — including testosterone — through the bloodstream.

Obesity lowers SHBG, which in turn lowers measured total testosterone even when the underlying hormonal axis is working normally. That's a big reason obesity can mimic low testosterone on a blood test, and why weight loss often raises the number. See the guide on HRT for men and GLP-1 medications.

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Related terms

Hypogonadism — A condition of low sex-hormone production. In men it means low testosterone with symptoms; importantly, the low testosterone that often accompanies obesity is frequently a reversible state ('pseudo-hypogonadism') rather than true, pathologic hypogonadism.
Testosterone replacement therapy (TRT) — Replacing testosterone in men who have hypogonadism (clinically low testosterone plus symptoms), delivered as a gel, injection, patch, or pellet. It is for a specific diagnosis, not a default treatment for the reversible low testosterone that often accompanies obesity.
Menopausal hormone therapy (MHT) — Estrogen, usually combined with a progestogen (when the uterus is present), used to relieve menopausal symptoms such as hot flashes and to protect bone. Often just called 'HRT.' It is associated with less visceral fat but is not a weight-loss treatment.
Hormone replacement therapy (HRT) — Treatment that replaces a hormone the body no longer produces in adequate amounts — most commonly estrogen (usually with a progestogen) for menopausal women, or testosterone for men with hypogonadism. It is not a weight-loss treatment and is separate from GLP-1 medications.

Related guides

HRT for men (testosterone) and GLP-1 medications: what the connection really is — Low testosterone and excess weight are linked — but the arrow often points from weight to testosterone, not the other way, and that changes when testosterone therapy actually helps. Here's who benefits from TRT, and why losing weight on a GLP-1 can raise testosterone on its own.
Hormone replacement therapy (HRT) and GLP-1 medications: an overview — HRT and GLP-1s are different tools that keep coming up together, because the life stages where people reach for hormones — menopause in women, low testosterone in men — are also times of weight and body-composition change. Here's how they relate, who benefits, and how to think about using them together.