What Does Wegovy Do? How It Works in Your Body, Organ by Organ

Written by Diana Gangan. Updated October 24, 2026.

Wegovy makes you less hungry, keeps you full longer after smaller meals, and steadies your blood sugar, so you eat less without a constant fight. Over about a year and a half, that adds up to around 15% of body weight lost at the standard 2.4 mg dose, and about 21% at the new 7.2 mg Wegovy HD dose. It also does things that have nothing to do with the scale: in people with heart disease it cut heart attacks, strokes and cardiovascular deaths by 20%, and it is approved to treat the liver disease MASH.

Here is what Wegovy does in each part of your body after the weekly injection, what the numbers look like, what it does not do, and what happens when you stop.

After you eat, cells in your gut release GLP-1 (glucagon-like peptide-1), a hormone that tells your brain food has arrived, tells your pancreas to release insulin, and slows your stomach. Natural GLP-1 lasts only a couple of minutes before the body breaks it down. Semaglutide is a modified version built to resist that breakdown and bind to a protein in the blood, so a single dose keeps working for about a week. In effect, Wegovy keeps your body's own "I've eaten" signal switched on. For the wider drug family, see GLP-1 drugs explained.

This is the effect people notice first, often within the first week or two. Hunger between meals fades, portions shrink on their own, and many people describe a quieting of constant thoughts about food. Trials that measured intake found people on semaglutide ate roughly 25% to 35% fewer calories at a buffet meal without being asked to. The effect is dose-related, which is why Wegovy starts at 0.25 mg and climbs over 16 weeks to 2.4 mg; the low doses are for your stomach to adjust, not for weight loss. See the Wegovy dosing schedule.

Semaglutide slows gastric emptying, the rate at which food moves from the stomach into the intestine. That is why a modest meal can leave you full for hours, and it is also the source of the most common side effects: nausea (about 44% of people in STEP 1), diarrhea (30%), vomiting (24%), constipation (24%) and burping. These are strongest after dose increases and usually ease within weeks. The slowing is most pronounced early in treatment and lessens over time. Eating smaller meals, avoiding fatty or very sweet foods and not lying down after eating help. Rarely, severe slowing (gastroparesis) or gallbladder problems occur. Our side effects page has the full list.

Semaglutide is the same molecule as Ozempic, a diabetes drug, so Wegovy lowers blood sugar too. It prompts the pancreas to release insulin when glucose is high and suppresses glucagon, the hormone that tells the liver to release sugar. In people with type 2 diabetes it lowers A1C by about 1.5 to 2 percentage points. In people without diabetes, blood sugar stays normal; because the insulin effect is glucose-dependent, Wegovy on its own does not cause dangerous lows. It can, however, if you also take insulin or a sulfonylurea, which is why those doses often need lowering. In the STEP 1 trial, 84% of people with prediabetes returned to normal blood sugar on semaglutide.

In STEP 1, about a third of people lost 20% or more of their body weight. The weight comes off fastest between months three and six, slows after month nine and plateaus somewhere between 12 and 18 months. We break down the timeline in how long Wegovy takes to work and the ranges in how much weight you can lose on Wegovy. For how the pill compares, see Wegovy pill vs injection.

This is the result that changed how doctors see the drug. In the SELECT trial, 17,604 adults with overweight or obesity and existing cardiovascular disease, but no diabetes, took semaglutide 2.4 mg or placebo for about three years. Semaglutide reduced the combined rate of heart attack, stroke and cardiovascular death by 20%. The benefit appeared early, before most of the weight loss, which suggests semaglutide acts on the heart and blood vessels directly as well as through weight. On the back of SELECT, FDA approved Wegovy in March 2024 to reduce cardiovascular risk in people with heart disease and excess weight.

In August 2025 Wegovy became the first GLP-1 drug approved for MASH (metabolic dysfunction-associated steatohepatitis, previously called NASH), a form of fatty liver disease with inflammation and scarring. In the ESSENCE trial, 62.9% of people on semaglutide had their MASH resolve without worsening scarring, versus 34.3% on placebo, and 37% saw scarring improve versus 22.4%. The approval covers adults with moderate to advanced fibrosis (stages F2 to F3) and is accelerated, meaning a longer confirmatory trial is still running.

The appetite effect fades as the drug leaves your body, roughly five to seven weeks after the last injection, and hunger returns to its old level. In the STEP 1 extension, people who stopped semaglutide and lifestyle support regained about 11.6 of the 17.3 percentage points they had lost by one year later. Blood pressure, blood sugar and cholesterol improvements mostly reversed too. That is why Wegovy is approved for long-term use and why stopping is best planned with a doctor. Our guide to what happens when you stop taking Wegovy covers tapering and maintenance.

Zepbound (tirzepatide) copies two gut hormones, GLP-1 and GIP, instead of one. In the SURMOUNT-5 head-to-head trial it produced about 20% weight loss versus 14% for Wegovy 2.4 mg over 72 weeks. Wegovy HD at 7.2 mg narrows that gap, and Wegovy alone has the heart-protection and MASH approvals. Side effects are similar. See Zepbound vs Wegovy for the full comparison.

Wegovy copies the gut hormone GLP-1 to lower appetite, slow digestion and steady blood sugar, which leads to about 15% weight loss at the standard dose and about 21% at the high dose. Beyond the scale, it reduces heart attacks and strokes in people with heart disease and treats MASH. It does not burn fat or change your metabolism, its effects stop when the drug stops, and its most common side effects come from the same slowed stomach that makes it work. For the long view on safety, read GLP-1 long-term side effects.

This article is for general information and is not medical advice. Talk to your doctor about whether Wegovy is right for you.