Semaglutide is the GLP-1 peptide that quieted hunger and learned to mend the liver.

Before the details

Semaglutide is a medicine. It is a man-made copy of a gut hormone called GLP-1 (a signal your body releases after you eat, telling you that you are full and helping control blood sugar). It is approved and used for type 2 diabetes, for long-term weight management, to lower the risk of heart attack and stroke in certain people, and — since 2025 — for a serious fatty-liver disease called MASH.

What does it do in the studies? In a large weight trial, people lost about 15% of their body weight over roughly a year ^[1]. In the liver trial, the inflamed, scarred liver healed in far more people on the drug than on a dummy injection ^[8]. People also often say their constant thoughts about food simply go quiet.

It is not gentle for everyone. Nausea and stomach upset are common, especially early on, and the weight tends to come back if the drug is stopped. What people report, the good and the hard, is on the effects page.

The liver, and the trial that taught this peptide to mend it

For most of its life semaglutide was known for hunger and blood sugar. In 2025 the record reached the liver. In the ESSENCE phase-3 trial — 1,197 adults with biopsy-confirmed MASH (metabolic dysfunction-associated steatohepatitis, a form of fatty-liver disease where fat, inflammation, and scarring build in the organ) and stage 2-3 fibrosis — once-weekly semaglutide 2.4 mg resolved the steatohepatitis without worsening scar tissue in 62.9% of participants, against 34.3% on placebo ^[8]. Fibrosis itself improved in 36.8% versus 22.4% ^[8].

That is the leading image of this digest: a peptide first prized for emptying the plate, shown to quiet the inflammation in the organ that the modern diet wears down first. The liver had no symptoms to announce the change. The biopsy did.

The hepatic finding does not stand alone. It sits at the far end of a long shelf of trials — diabetes, weight, heart, kidney — each of which read the same molecule through a different organ.

What the broader Semaglutide record has measured

Begin with weight, where the numbers are largest. In the STEP 1 randomized trial, once-weekly subcutaneous semaglutide 2.4 mg produced a mean body-weight change of -14.9% from baseline to week 68, against -2.4% with placebo, in adults with overweight or obesity and no diabetes ^[1] — a treatment difference of roughly twelve percentage points. The mechanism is mostly in the brain: the drug reaches appetite circuits and turns down the drive to eat ^[4].

The heart has its own chapter. In SELECT, a trial of 17,604 adults with established cardiovascular disease and excess weight but no diabetes, semaglutide cut major adverse cardiovascular events by 20% versus placebo (hazard ratio 0.80; 95% CI 0.72-0.90) ^[3]. In SUSTAIN-6, among people with type 2 diabetes at high cardiovascular risk, the same composite fell (HR 0.74; 95% CI 0.58-0.95) — though diabetic-retinopathy complications were more frequent in those undergoing rapid blood-sugar correction (HR 1.76) ^[2].

The kidney answered too. In the FLOW trial of type 2 diabetes with chronic kidney disease, semaglutide reduced major kidney events by 24% (HR 0.76; 95% CI 0.66-0.88) ^[6]. Five organs, one molecule, read across a decade of Semaglutide research.

A peptide built to last a week

Native GLP-1 lives about two minutes before the body's enzymes dismantle it. Semaglutide was engineered to last roughly a week. A single swapped amino acid blocks the enzyme (DPP-4) that would chew it apart, and a fatty-acid tail lets it cling reversibly to albumin, the most abundant protein in blood, which carries it slowly past the kidney's filters ^[9]. Its elimination half-life — the time for blood levels to fall by half — is about one week, so the drug is effectively gone roughly five weeks after the last dose ^[9].

That slow clock is why it is given once weekly by injection, and why a once-daily tablet exists at all. To learn what the molecule is and how it was made, start with what is semaglutide; to follow the signal from blood to brain, read how does semaglutide work.

How to read this site

This is an editorial reading room, not a clinic and not a pharmacy. It summarizes the published, peer-reviewed record on semaglutide and the approved-label facts that surround it. It does not recommend a dose for any person, and the doses named here are the ones documented in trials and labeling, reported in the third person.

The trials are laid out on the Semaglutide research page. The honest human texture — what people report it feels like, and who has reason to be cautious — is on the Semaglutide effects page. The doses studied are on the dosage page. Every quantitative claim on this site is tied to a numbered study in the Semaglutide references.