Metreleptin vs Leptin
Written by Aaron CuhaReviewed Sep 2026
The short answer
The hormone and its lab made form. The key number is not how much weight either takes off, but in whom. Replacing leptin changes everything for people who make almost none of it, and does close to nothing in ordinary obesity. A 127 person trial in 1999 already showed that.
- Metreleptin people
- 0
- Metreleptin nulls
- 0
- Leptin people
- 844
- Leptin nulls
- 0
Dose
No human dose established
No published study on this page has given this compound to people and reported a result.
1 human study where nobody was given it
Dose
Approved medicine. No human dose established for unlabelled uses
Labeled amounts sit on the prescribing information. This page records what trials measured, not a personal dose.
Metreleptin (Myalept) was FDA-approved on 24 February 2014 (BLA 125390, Chiesi). It is used alongside diet to treat problems caused by too little leptin in people with generalised lipodystrophy, a rare condition where the body cannot store fat normally, whether they were born with it or got it later. Listed as Prescription in the FDA drug database (Drugs@FDA) on 11 September 2026. It carries the FDA's strongest (boxed) warning, for antibodies that block metreleptin and for T-cell lymphoma, a blood cancer. It is only handed out through a restricted safety programme (REMS). It is not for use in obesity. Natural leptin is not a product.
First-hand reports are counted on each profile and never added together. This page sets two published records side by side. It does not pick a winner.
Column A
MetreleptinMetreleptin (Myalept), recombinant human leptin analogue
Life-changing in people who make almost no leptin, and useless for ordinary obesity. The clearest case on this site of a hormone that only works when you are short of it.
Column B
LeptinLeptin (with metreleptin, Myalept, the approved recombinant analogue)
Leptin is a hormone your fat makes. It tells the brain how much energy you have stored. For the rare people born without it, getting it back changes their lives. In ordinary obesity, a 1999 study of 127 people found only small weight loss, and no drug came of it. A version called metreleptin is approved for a rare disease where the body loses its fat, with the FDA's strongest warning on the label.
Side by side, on the facts we can check
| What we compare | Metreleptin | Leptin |
|---|---|---|
| Category | Hormone | Metabolic |
| FDA status | FDA-approved as Myalept for problems caused by too little leptin in generalised lipodystrophy, a rare condition where the body has almost no fat. It carries a boxed warning, the FDA's strongest, for two risks. The body can make antibodies that block the drug, and it can raise the risk of T-cell lymphoma, a blood cancer. It is only supplied through a restricted program. Not approved for obesity or partial lipodystrophy. | Metreleptin (Myalept) was FDA-approved on 24 February 2014 (BLA 125390, Chiesi). It is used alongside diet to treat problems caused by too little leptin in people with generalised lipodystrophy, a rare condition where the body cannot store fat normally, whether they were born with it or got it later. Listed as Prescription in the FDA drug database (Drugs@FDA) on 11 September 2026. It carries the FDA's strongest (boxed) warning, for antibodies that block metreleptin and for T-cell lymphoma, a blood cancer. It is only handed out through a restricted safety programme (REMS). It is not for use in obesity. Natural leptin is not a product. |
| Half-life | Roughly three to four hours after subcutaneous injection, which is why it is dosed daily. | 3.8 to 4.7 hours |
| Molecular weight | 16.2 kDa. A 147-amino-acid recombinant protein. | About 16.15 kDa (metreleptin, 147 residues, FDA label); native mature leptin is 146 residues, UniProt P41159, from an 18,641 Da 167-residue precursor |
| How it works | Metreleptin is a lab-made copy of human leptin, with one extra amino acid (methionine) added. Fat cells release leptin in line with how much fat you carry. It acts on the brain's hunger center (the hypothalamus). It turns down the nerve cells that drive hunger (NPY and AgRP) and turns up the ones that curb it (POMC). It also tells the systems for reproduction, thyroid and immunity that there is enough food. With no leptin, all those signals read as starving, no matter how much energy the body has stored. That is why replacing it does so much. In ordinary obesity, leptin is already high and the brain has stopped responding, so adding more changes little. | What we know in people comes from those born without leptin and from giving it back. Leptin docks on a receptor on the brain cells that control hunger. It turns down the cells that drive hunger, called NPY and AgRP cells. It turns up the cells that make you feel full, called POMC cells. People with no leptin are always hungry and get very obese very young. They also do not go through puberty normally, have thyroid changes and have weak immune cells. All of that reverses when leptin is given back. In lipodystrophy, leptin lowers blood sugar, blood fats and liver fat. It also cuts how much people eat and how many calories they burn at rest. In ordinary obesity, leptin in the blood is already high. Adding more has only a small effect, and a bigger dose gives a bit more. That is called leptin resistance. How it works has mostly been studied in rats and mice. The ideas include less leptin getting into the brain, weaker signalling and a brake protein called SOCS3. Metreleptin is lab-made human leptin, grown in E. coli bacteria. It is 147 building blocks long. Natural leptin is 146. The extra one is a methionine added at the front. The kidneys clear it from the body. Antibodies against the drug are expected to slow that down. |
| Studies in people | 1 | 7 |
| Evidence | Preliminary: 1 human study where nobody was given it | Moderate: 6 completed trials, 844 people given it |
| Legal status, US | FDA-approved, prescription only | FDA-approved, prescription only |
Frequently asked questions
What is the difference between Metreleptin and Leptin?
Metreleptin: Life-changing in people who make almost no leptin, and useless for ordinary obesity. The clearest case on this site of a hormone that only works when you are short of it. Leptin: Leptin is a hormone your fat makes. It tells the brain how much energy you have stored. For the rare people born without it, getting it back changes their lives. In ordinary obesity, a 1999 study of 127 people found only small weight loss, and no drug came of it. A version called metreleptin is approved for a rare disease where the body loses its fat, with the FDA's strongest warning on the label.
Which has stronger research evidence, Metreleptin or Leptin?
Each compound gets a band worked out from facts we counted, with the math shown. Metreleptin is Preliminary (1 human study where nobody was given it). Leptin is Moderate (6 completed trials, 844 people given it). That counts how much has been done in people. It does not rate whether either one works, and neither one is called the winner.
Are Metreleptin and Leptin FDA-approved?
Metreleptin: FDA-approved as Myalept for problems caused by too little leptin in generalised lipodystrophy, a rare condition where the body has almost no fat. It carries a boxed warning, the FDA's strongest, for two risks. The body can make antibodies that block the drug, and it can raise the risk of T-cell lymphoma, a blood cancer. It is only supplied through a restricted program. Not approved for obesity or partial lipodystrophy.. Leptin: Metreleptin (Myalept) was FDA-approved on 24 February 2014 (BLA 125390, Chiesi). It is used alongside diet to treat problems caused by too little leptin in people with generalised lipodystrophy, a rare condition where the body cannot store fat normally, whether they were born with it or got it later. Listed as Prescription in the FDA drug database (Drugs@FDA) on 11 September 2026. It carries the FDA's strongest (boxed) warning, for antibodies that block metreleptin and for T-cell lymphoma, a blood cancer. It is only handed out through a restricted safety programme (REMS). It is not for use in obesity. Natural leptin is not a product..
Reviewed Sep 2026. This page puts two published records side by side. It is for learning, and it is not medical advice. When this site shows a dose, it is the dose a trial or a clinic actually used, or what people say they did, with the source attached. None of it tells you what to take.