Leptin
Evidence: DEvidence: AGrade D — Applies to native, unmodified (146-amino-acid) human Leptin. Every human interventional/administration source in this batch's Leptin manifest -- both the historical congenital-leptin-deficiency replacement programme (PMID 10486419, 15472169, 12393845) and the common-obesity dose-escalation RCT (PMID 10546697) -- administered recombinant methionyl leptin (147 amino acids, +1 N-terminal methionine), an analogue-class material relative to native, unmodified leptin, not exact-subject native-Leptin administration. Per this project's governing rule, analogue-program-context evidence cannot itself establish an exact/native-subject grade. What remains as native Leptin's own evidence is: (1) well-established observational/physiological human endocrinology concerning endogenous native leptin itself (levels correlate inversely with adiposity and fall with fasting; confirmed LEP-gene mutation carriers have undetectable native leptin and a severe early-onset obesity phenotype); and (2) strong, real, but analogue-class contextual evidence (the dramatic and consistent deficiency-reversal effect of recombinant methionyl leptin replacement, preserved as contextual, not exact-subject, evidence). No exact-sequence, unmodified native-Leptin human administration/interventional study was identified in this batch's manifest or in a dedicated fresh check (per Stage 2BR remediation). The common-obesity evidence (Heymsfield, PMID 10546697) is likewise analogue-class, not exact native-subject evidence, and is not separately graded -- it is preserved as contextual claim evidence instead of its own letter grade..
Grade A — Metreleptin (Myalept) generalized-lipodystrophy clinical and regulatory programme.
Metreleptin is recombinant methionyl human leptin, differing from endogenous mature human leptin by one added N-terminal methionine. Its FDA approval (2014) is strictly limited to complications of leptin deficiency in congenital or acquired GENERALIZED lipodystrophy, carries a boxed warning for anti-metreleptin neutralizing antibodies and T-cell lymphoma risk, and is dispensed only through the Myalept REMS Program. This approval and its boxed warning are specific to this product and this indication -- they do not establish native leptin's own evidence grade, and they explicitly do NOT extend to partial lipodystrophy, HIV-related lipodystrophy, common obesity, or any metabolic condition without confirmed generalized lipodystrophy, per the product's own official Limitations of Use. This related-programme grade is scoped specifically to Metreleptin/Myalept's own FDA-regulated generalized-lipodystrophy programme; it is separate from, and does not retroactively confer FDA-approval status upon, the earlier (1999-2004) historical recombinant methionyl-leptin congenital-leptin-deficiency research programme (Farooqi/Gibson et al.), which used the same general molecular class of material but was investigational, in a different patient population, and predated Metreleptin's own 2014 approval by a decade or more; that historical programme is described in Leptin's own claims rather than folded into this related-programme field.
Gastrointestinal / Gut-Hormone Signaling
Evidence Snapshot
What this grade covers
Applies to native, unmodified (146-amino-acid) human Leptin. Every human interventional/administration source in this batch's Leptin manifest -- both the historical congenital-leptin-deficiency replacement programme (PMID 10486419, 15472169, 12393845) and the common-obesity dose-escalation RCT (PMID 10546697) -- administered recombinant methionyl leptin (147 amino acids, +1 N-terminal methionine), an analogue-class material relative to native, unmodified leptin, not exact-subject native-Leptin administration. Per this project's governing rule, analogue-program-context evidence cannot itself establish an exact/native-subject grade. What remains as native Leptin's own evidence is: (1) well-established observational/physiological human endocrinology concerning endogenous native leptin itself (levels correlate inversely with adiposity and fall with fasting; confirmed LEP-gene mutation carriers have undetectable native leptin and a severe early-onset obesity phenotype); and (2) strong, real, but analogue-class contextual evidence (the dramatic and consistent deficiency-reversal effect of recombinant methionyl leptin replacement, preserved as contextual, not exact-subject, evidence). No exact-sequence, unmodified native-Leptin human administration/interventional study was identified in this batch's manifest or in a dedicated fresh check (per Stage 2BR remediation). The common-obesity evidence (Heymsfield, PMID 10546697) is likewise analogue-class, not exact native-subject evidence, and is not separately graded -- it is preserved as contextual claim evidence instead of its own letter grade.
Regulatory Context
Native Leptin is an endogenous hormone and is not itself an FDA-approved drug product. Metreleptin (Myalept, approved 2014) is an FDA-approved recombinant leptin analogue strictly indicated for complications of leptin deficiency in congenital or acquired generalized lipodystrophy, carries a boxed warning for anti-metreleptin neutralizing antibodies and T-cell lymphoma risk, and is dispensed only through the Myalept REMS Program. It is explicitly NOT indicated for partial lipodystrophy, HIV-related lipodystrophy, or any metabolic condition without confirmed generalized lipodystrophy. The historical (1999-2004) congenital-leptin-deficiency research programme that used the same general molecular class of recombinant methionyl leptin was investigational and was never itself an FDA-approved product.
Research Takeaway
Leptin is a 146-amino-acid adipocyte-derived hormone that signals energy sufficiency to the hypothalamus. Congenital leptin deficiency is a rare condition causing severe early-onset obesity due to absent or non-functional endogenous leptin.
Evidence boundary: Do not use to imply Metreleptin is identical to endogenous leptin. Do not use this identity statement, or any source cited here, to imply that the congenital-deficiency replacement trials (lep-c2) administered literally unmodified native leptin.
See all 4 evidence claims →Quick Summary
Leptin is a hormone made by fat tissue that signals energy sufficiency to the brain. In the rare condition of confirmed congenital leptin deficiency, replacement therapy with recombinant methionyl leptin -- administered in a historical research programme conducted years before Metreleptin's own approval, though molecularly the same general class of material -- has produced dramatic, sustained reversal of severe obesity and related metabolic problems. In common obesity, where leptin deficiency is not present, controlled research using the same class of recombinant leptin shows a much weaker and highly variable response -- consistent with widespread leptin resistance -- and leptin has never been approved as a general obesity treatment. Metreleptin (Myalept) is the FDA-approved recombinant leptin product formalized from this molecular class, approved only for generalized lipodystrophy and carrying its own boxed safety warning.
Mechanism & Research Overview
Leptin is a hormone made by fat tissue that signals energy sufficiency to the brain. In the rare condition of confirmed congenital leptin deficiency, replacement therapy with recombinant methionyl leptin -- administered in a historical research programme conducted years before Metreleptin's own approval, though molecularly the same general class of material -- has produced dramatic, sustained reversal of severe obesity and related metabolic problems. In common obesity, where leptin deficiency is not present, controlled research using the same class of recombinant leptin shows a much weaker and highly variable response -- consistent with widespread leptin resistance -- and leptin has never been approved as a general obesity treatment. Metreleptin (Myalept) is the FDA-approved recombinant leptin product formalized from this molecular class, approved only for generalized lipodystrophy and carrying its own boxed safety warning.
Evidence Claims
Individual scientific statements drawn from the sources cited below, each shown with the specific evidence boundary that statement does not establish.
Supported
Leptin is a 146-amino-acid adipocyte-derived hormone that signals energy sufficiency to the hypothalamus. Congenital leptin deficiency is a rare condition causing severe early-onset obesity due to absent or non-functional endogenous leptin.
Does not establish
Evidence boundary: Do not use to imply Metreleptin is identical to endogenous leptin. Do not use this identity statement, or any source cited here, to imply that the congenital-deficiency replacement trials (lep-c2) administered literally unmodified native leptin.
Sources: Effects of Recombinant Leptin Therapy in a Child with Congenital Leptin Deficiency
Supported
In patients with genetically confirmed congenital leptin deficiency, subcutaneous administration of recombinant methionyl leptin -- in a historical research programme (1999-2004) that predates and is distinct from Metreleptin's own 2014 FDA approval, though molecularly the same general class of material -- produced a dramatic and sustained reversal of the severe obesity phenotype, including reduced food intake, reduced body fat, improved insulin sensitivity, and improved lipid profile, documented over periods up to 4 years.
Does not establish
Evidence boundary: Evidence comes from a small number of very well-characterized individual cases (not a large-RCT base), all administered recombinant methionyl leptin -- analogue-class material relative to native, unmodified 146-amino-acid leptin, never literally unmodified endogenous leptin. Per this project's governing rule, analogue-program-context evidence cannot itself establish an exact/native-subject grade -- this finding is preserved here as powerful contextual evidence of leptin-pathway biology and of the historical recombinant methionyl-leptin congenital-deficiency replacement programme, not as exact-subject native-Leptin efficacy evidence. Must not be generalized to leptin-sufficient/common obesity (see lep-c3). Do not present this historical programme's methionylated recombinant leptin material as exact-subject native-Leptin evidence, and do not describe it as 'native-Leptin exact-subject administration.'
Sources: Effects of Recombinant Leptin Therapy in a Child with Congenital Leptin Deficiency; Congenital Leptin Deficiency Due to Homozygosity for the Delta133G Mutation: Report of Another Case and Evaluation of Response to Four Years of Leptin Therapy; Beneficial Effects of Leptin on Obesity, T Cell Hyporesponsiveness, and Neuroendocrine/Metabolic Dysfunction of Human Congenital Leptin Deficiency
Supported
In common obesity (i.e., without confirmed leptin deficiency), a randomized controlled dose-escalation trial of recombinant leptin found a statistically significant but highly variable, dose-dependent group-level weight-loss effect; many individual participants showed little or no response, and injection-site reactions were the most common adverse effect. This has not translated into an approved obesity indication for leptin.
Does not establish
Evidence boundary: A single 1999 RCT; the material administered was recombinant methionyl human leptin -- the same analogue-class material as the historical congenital-deficiency programme (lep-c2) and molecularly the precursor class to Metreleptin -- not literally unmodified endogenous leptin. The effect described is a group-level statistical signal with substantial individual variability, not a reliable individual-level treatment effect, and is analogue-program-context evidence, not exact-subject native-Leptin evidence. Do not state 'leptin causes weight loss in obesity' without this variability/non-response caveat; do not conflate this population with the congenital-deficiency population in lep-c2.
Supported
Metreleptin (Myalept) is recombinant methionyl human leptin, differing from endogenous mature human leptin by one added N-terminal methionine. Its FDA approval, boxed warning, and REMS restriction are specific to its approved indication (generalized lipodystrophy) and do not apply to native leptin or to any other use of leptin.
Does not establish
Evidence boundary: Never state or imply Metreleptin's boxed warning (lymphoma, neutralizing antibodies) applies to native leptin; never state Metreleptin is approved for common obesity, partial lipodystrophy, or HIV-related lipodystrophy; and never state Metreleptin's 2014 approval retroactively confers FDA-approved status on the historical (1999-2004) congenital-deficiency research programme, which was investigational and never itself an approved product.
Sources: FDA Label / DailyMed Record for MYALEPT (Metreleptin)
Safety & Evidence Limitations
Considerations reported in the sources cited on this page — not a complete list of every possible risk, and not medical advice.
Higher-Priority Safety Consideration
Myalept's official label carries a boxed warning for anti-metreleptin neutralizing antibodies (which may inhibit endogenous leptin action and reduce efficacy, with reported severe infections and worsening metabolic control) and for T-cell lymphoma (reported in generalized-lipodystrophy patients whether or not treated with Myalept). This is a risk of the APPROVED PRODUCT in its approved population, not of native leptin.Safety Consideration
A controlled RCT in obese and lean adults without confirmed leptin deficiency found a statistically significant but highly individually variable dose-response weight-loss signal (SD exceeding the mean effect at the highest dose) -- consistent with widespread leptin resistance in common obesity. This has never translated into an approved obesity indication. The material administered was recombinant methionyl leptin, the same analogue class used in the congenital-deficiency programme -- not exact-sequence native leptin.Safety Consideration
The exact material administered in the foundational 1999/2002/2004 congenital-leptin-deficiency trials, AND in the 1999 Heymsfield common-obesity RCT, was recombinant methionyl leptin (same molecular class later formalized as Metreleptin), not literally unmodified native leptin. This is the central reason native Leptin's own evidenceGrade is D, not B.
Research Areas Being Studied
Research areas discussed on this page reflect the Gastrointestinal / Gut-Hormone Signaling category and the sources cited below.
Findings Reported in Studies
Educational summary only — reported in cited studies, not a claim of proven benefit.
- Congenital Leptin Deficiency Due to Homozygosity for the Delta133G Mutation: Report of Another Case and Evaluation of Response to Four Years of Leptin Therapy (2004):
- Beneficial Effects of Leptin on Obesity, T Cell Hyporesponsiveness, and Neuroendocrine/Metabolic Dysfunction of Human Congenital Leptin Deficiency (2002):
- Effects of Recombinant Leptin Therapy in a Child with Congenital Leptin Deficiency (1999):
- Recombinant Leptin for Weight Loss in Obese and Lean Adults: A Randomized, Controlled, Dose-Escalation Trial (1999):
Study Tables by Evidence Type
Human Studies & Clinical Data
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| Congenital Leptin Deficiency Due to Homozygosity for the Delta133G Mutation: Report of Another Case and Evaluation of Response to Four Years of Leptin Therapy | 2004 | single patient, Delta133G homozygous congenital leptin deficiency, 4-year subcutaneous therapy | 4 years of subcutaneous recombinant methionyl leptin therapy provided additional evidence for the sustained beneficial effects of leptin replacement on fat mass, hyperinsulinemia, and hyperlipidemia. | Same ANALOGUE_PROGRAM_CONTEXT-class material classification as PMID 10486419 per Stage 2BR. Single patient, open-label. | |
| Beneficial Effects of Leptin on Obesity, T Cell Hyporesponsiveness, and Neuroendocrine/Metabolic Dysfunction of Human Congenital Leptin Deficiency | 2002 | congenital-leptin-deficient patients | Recombinant methionyl leptin replacement in congenital-leptin-deficient patients produced broader immune (T-cell hyporesponsiveness reversal) and neuroendocrine/metabolic benefits. | ANALOGUE_PROGRAM_CONTEXT-class material per Stage 2BR; must not be generalized to common obesity or leptin-sufficient individuals. | |
| Effects of Recombinant Leptin Therapy in a Child with Congenital Leptin Deficiency | 1999 | single 9-year-old female patient, congenital leptin deficiency (frameshift mutation, undetectable serum leptin) | Subcutaneous recombinant methionyl leptin (once daily) produced reversal of severe early-onset obesity phenotype, reduced food intake and body fat. | Material administered was RECOMBINANT METHIONYL LEPTIN (147 amino acids, +1 N-terminal methionine relative to endogenous 146-amino-acid mature leptin) -- ANALOGUE_PROGRAM_CONTEXT-class material relative to native leptin, per Stage 2BR correction, NOT literally unmodified endogenous leptin. Single patient (n=1), open-label, no control arm. Must not be presented as exact-subject native-Leptin administration evidence. | |
| Recombinant Leptin for Weight Loss in Obese and Lean Adults: A Randomized, Controlled, Dose-Escalation Trial | 1999 | obese and lean adults WITHOUT confirmed leptin deficiency, randomized controlled dose-escalation | A statistically significant dose-dependent group-level weight-loss signal (up to -7.1 kg at the highest dose, 0.30 mg/kg, at 24 weeks, P=.01; fat loss >95% of weight loss at the two highest doses), but with enormous individual-level variability (SD 8.5 kg on a 7.1 kg mean at the highest dose) -- many individual subjects had little or no response. Injection-site reactions were the most common adverse effect. | ANALOGUE_PROGRAM_CONTEXT-class (methionylated recombinant) material per Stage 2BR, same class as the congenital-deficiency programme -- NOT exact-sequence native leptin. Must never be stated as 'leptin causes reliable weight loss in obesity generally.' |
Animal / Cell / Preclinical Data
No Animal / Cell / Preclinical Data Listed Yet
This section will be updated as sources are added.
Regulatory Documents & Official Trial Registries
| Title | Year | Population / Model | Dose / Duration / Finding | Safety Notes | Source |
|---|---|---|---|---|---|
| FDA Label / DailyMed Record for MYALEPT (Metreleptin) | 2014 | Metreleptin, a 147-amino-acid nonglycosylated polypeptide produced in E. coli, differs from endogenous mature human leptin (146 amino acids) by the addition of a methionine residue at its amino terminus. FDA-approved 2014 for complications of leptin deficiency in congenital or acquired GENERALIZED lipodystrophy, as an adjunct to diet. BOXED WARNING (verbatim): (1) anti-metreleptin neutralizing antibodies have been identified in treated patients, which may inhibit endogenous leptin action and/or cause loss of efficacy, with severe infection and/or worsening metabolic control reported; (2) T-cell lymphoma has been reported in patients with acquired generalized lipodystrophy, both treated and not treated with Myalept. Explicit Limitations of Use: not established for partial lipodystrophy; not established for liver disease/NASH; not indicated for HIV-related lipodystrophy; not indicated for metabolic disease without concurrent evidence of generalized lipodystrophy. Available only through the Myalept REMS Program. | Boxed warning, REMS restriction, and approved indication are specific to this product and do not apply to native leptin or to the historical (1999-2004, investigational, non-FDA-approved) congenital-deficiency research programme. | No source link available |
Anecdotal Reported Patterns — Not Medical Advice
Anecdotal Reported Patterns — Not Medical Advice
Reported dosing patterns are included for educational context only. They are self-reported, unverified, not medical advice, and not instructions for human use. Community-submitted patterns are not yet available in this Phase 1 prototype; this section is a placeholder reserved for moderated, aggregated community data.
Lab Markers to Discuss With a Clinician
Educational topics only — not self-monitoring instructions.
FAQ
Disclaimer
Educational information only. This page summarizes published research on endogenous leptin and its FDA-approved analogue, Metreleptin. It does not constitute medical advice, a treatment recommendation, or dosing guidance for any leptin-related substance or its analogue drug product.
Educational use only. This content is provided for informational and research-summary purposes only. It is not medical advice, not a treatment recommendation, not a dosing guide, and not a substitute for care from a licensed medical professional. Nothing here is intended to diagnose, treat, cure, prevent, or mitigate disease. Reported dosing patterns, when shown elsewhere on the site, must be labeled either as Study / Trial Dosing or Anecdotal Reported Patterns — Not Medical Advice. Community reports are self-reported, unverified, and not scientific proof.
Community-reported experiences, once enabled, must be displayed only as moderated, anonymized, or aggregated data. They are anecdotal, self-reported, unverified, and should never be presented as proof of safety, efficacy, or expected results.
Content status: Published. Last updated 2026-08-26.
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