Metreleptin
Metreleptin is an injectable man-made form of leptin approved for generalised lipodystrophy, where the body cannot produce enough leptin - it is not a treatment for common obesity.
Plain English
Patient-Friendly Explanation
Leptin is the hormone fat cells release to tell the brain how much energy is stored, and metreleptin is a laboratory-made version given as a daily injection under the skin. It is approved for a rare condition called generalised lipodystrophy, in which the body has almost no fat tissue and therefore makes almost no leptin, causing relentless hunger, very high blood fats, severe insulin resistance and fatty liver. In that situation replacing leptin transforms the disease. It does not work for ordinary obesity, because people living with obesity usually have plenty of leptin already - the problem is that the brain has become resistant to it, so adding more does not help. This is an important distinction that separates a targeted rare-disease therapy from a general weight-loss medicine.
Medical
Clinical Definition
Metreleptin is recombinant methionyl human leptin, administered by subcutaneous injection, and is approved for the treatment of complications of leptin deficiency in patients with generalised lipodystrophy (and, in some jurisdictions, partial lipodystrophy), as well as for congenital leptin deficiency. In these leptin-deficient states it reverses hyperphagia, reduces hypertriglyceridaemia, improves hepatic steatosis and markedly improves insulin sensitivity, often allowing major reductions in insulin requirements. Therapy requires monitoring because neutralising anti-leptin antibodies can develop and abolish efficacy, and serious risks include severe hypoglycaemia after abrupt discontinuation in insulin-treated patients, pancreatitis and, in patients with acquired generalised lipodystrophy, reports of T-cell lymphoma. Metreleptin has not demonstrated meaningful efficacy in common obesity, where circulating leptin is typically elevated and central leptin signalling is impaired - obesity is a state of leptin resistance rather than leptin deficiency, and this is why leptin itself failed as a general anti-obesity therapy. Dosing, monitoring and continuation decisions require specialist experience.
Key Insight
Why It Matters
Patients sometimes ask why leptin is not sold as a weight-loss injection when it is the hormone that controls appetite. Understanding the difference between leptin deficiency and leptin resistance explains the answer - and it is a good example of why targeted, evidence-based treatment matters more than a promising headline.
Sources
Reviewed against standard medical references.
Medically reviewed by
Family Physician & Registered Acupuncturist, Accord Medical Clinic. MBBS (NUS), Graduate Diploma in Family Medicine (NUS), Graduate Diploma in Acupuncture (Singapore College of TCM).
Last reviewed: September 2026
This page is general health education, not medical advice. Whether any treatment is appropriate for you is a decision made in consultation after assessment.
