PharmaceuticalMetabolicThyromimeticTR-beta agonistHepatic

Resmetirom (MGL-3196)

Also known as MGL-3196 · Rezdiffra

Written by enwyReviewed 5 Aug 20261 sources0 comments

Resmetirom is a liver-directed, thyroid hormone receptor beta-selective agonist approved in 2024 (as Rezdiffra) for metabolic dysfunction-associated steatohepatitis. Its TR-beta selectivity lowers liver fat and cholesterol while sparing the heart and bone, making it of interest as a cleaner thermogenic than T3.

01 Overview

Resmetirom was designed to activate the beta thyroid receptor found predominantly in the liver, reproducing the favourable lipid and hepatic-fat effects of thyroid hormone while avoiding the cardiac and skeletal effects mediated by TR-alpha. It gained full FDA approval for MASH with liver fibrosis, backed by large randomised trials.

Its clinical pedigree and hepatic selectivity make it attractive to physique users seeking fat loss and improved lipids without T3-style tachycardia. It is a genuine prescription drug, not a research chemical, though off-label metabolic use is unstudied.

02 Mechanism

Selective agonist of thyroid hormone receptor beta with liver-targeted uptake, upregulating hepatic fat oxidation, LDL-receptor expression and cholesterol clearance while minimally engaging cardiac TR-alpha.

03 Dosing

Tier	Dose	Route	Notes
MASH (approved)	80–100 mg/day	Oral	Weight-based: 80 mg <100 kg, 100 mg >=100 kg

04 Effects

Effect	Magnitude	Evidence
Reduced liver fatMarked reduction in liver fat content on MRI in trials.	-30% or more hepatic fat	Clinical
Lower LDL and lipidsTR-beta activation improves the atherogenic lipid profile.	LDL, apoB, triglycerides down	Clinical
Cardiac and bone sparingSelectivity avoids the tachycardia and bone loss of non-selective thyroid hormone.		Clinical

05 Side effects

Effect	Severity	Frequency	Evidence	Countermeasures
Diarrhoea and nauseaGastrointestinal upset, usually transient, at treatment initiation.	Mild	Common early	Clinical
Hepatic enzyme changes / drug interactionsTransaminase changes and significant interactions with statins via CYP/OATP.	Moderate	Uncommon	Clinical

06 Legal status

United States

FDA-approved (Rezdiffra, 2024)

as of Jan 2026

07 References

Resmetirom in NASH with fibrosis (MAESTRO-NASH)New England Journal of Medicine, 2024

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.