Semaglutide

The drug that started the modern weight-loss era, and still the one with the deepest heart-protection data.

Evidence: AApproved what's this?
Grade A. Large outcome trials across obesity, diabetes, heart and kidney disease.
Also known as: Ozempic · Wegovy · Rybelsus (oral) · oral Wegovy
Class: GLP-1 receptor agonist. Approved prescription medicine, Novo Nordisk.

The 30-second version

WhatAn engineered copy of the gut hormone GLP-1 that lasts a week instead of minutes.

ResultsAbout 15% weight loss at 68 weeks (STEP 1) and 20% fewer major cardiovascular events (SELECT).

The honest catchTirzepatide now produces more weight loss, and weight tends to come back after stopping.

What it is

After a meal your gut releases GLP-1, which is broken down within minutes. Semaglutide is a modified GLP-1 with a fatty-acid chain and a couple of amino-acid swaps. Those changes protect it from breakdown and let it ride on albumin, so one injection lasts a week. It comes as Ozempic (diabetes), Wegovy (weight, at a higher dose), Rybelsus (a daily tablet) and, since late 2025, an oral Wegovy tablet.

It activates only one receptor, which makes it the baseline of the incretin class. Its advantage over newer, stronger drugs is evidence. It's the only one here with a completed cardiovascular-outcomes trial in people without diabetes.

How it works

Weekly signal. Keeps the after-meal GLP-1 message switched on for seven days.

Brain. Reduces hunger and increases fullness in the hypothalamus, so eating less takes less willpower.

Stomach. Slows emptying, so fullness lasts longer.

Pancreas. Releases insulin when glucose is high and lowers glucagon, which steadies blood sugar.

Vessels. Lowers inflammation, blood pressure and lipids. Part of the heart benefit is independent of weight loss.

What the research shows

STEP 1: 2.4 mg weekly produced about 15% weight loss over 68 weeks in adults with obesity and no diabetes¹. SUSTAIN established its glucose control in type 2 diabetes. SELECT enrolled more than 17,000 adults with heart disease and overweight but no diabetes, and found a 20% reduction in heart attack, stroke and cardiovascular death². Later trials added kidney protection in diabetic kidney disease and resolution of the liver disease MASH in about two-thirds of patients.

In 2025 a head-to-head trial showed tirzepatide produces more weight loss (20.2% vs 13.7%). For heart-outcome data, semaglutide is still the reference.

Tirzepatide now leads on weight loss. Semaglutide leads on proof that it protects the heart.

Evidence at a glance

Use	Grade	Best evidence	Main gap	Read
Weight loss	AApproved	~15% at 68 weeks¹	Regain after stopping	Strong, proven
Cardiovascular	AApproved	20% fewer major events²	At-risk groups	Landmark
Type 2 diabetes	AApproved	Strong glucose control	—	First-line
Kidney, liver	AApproved	Kidney protection; MASH resolution	Specific groups	Expanding

Dosing: the approved schedule

Prescription medicine. This schedule comes from the Wegovy label and is shown so you can understand it. Changes to your dose belong with your doctor.

Step	Weekly dose	Weeks	What to watch
1	0.25 mg	1–4	Tolerance only. First nausea wave.
2	0.5 mg	5–8	Appetite effect starts
3	1.0 mg	9–12	Hydration and constipation
4	1.7 mg	13–16	Make sure you are still eating enough protein
5	2.4 mg	17 +	Maintenance. 1.7 mg is an accepted fallback.

If a step is too rough, hold the lower dose for another four weeks before trying again. For diabetes (Ozempic), the steps are the same up to 1.0 mg and top out at 2.0 mg. The oral tablet is taken daily on an empty stomach with a sip of water, then nothing for 30 minutes.

Preparing & storing

Pens are refrigerated before first use and can then be kept at room temperature for the period stated on the label. Lyophilised material is reconstituted with bacteriostatic water, swirled and refrigerated. Inject on the same weekday each week, rotating abdomen, thigh and arm.

Reported side effects

Nausea, vomiting, diarrhoea, constipation, abdominal pain, worst during step-ups
Gallstones and gallbladder inflammation with rapid weight loss
Muscle loss if protein intake and training are neglected
Facial volume loss ("Ozempic face") from overall fat loss
Rare: pancreatitis. Boxed warning for thyroid C-cell tumours seen in rodents.

Who should avoid it

Personal or family history of medullary thyroid cancer or MEN2
History of pancreatitis
Pregnancy; stop before trying to conceive
Don’t stack with tirzepatide or retatrutide (CagriSema is a designed combination, not a home stack)
Insulin and sulfonylurea users: doses need review

Regulatory status checked Oct 2026

Body	Status	Detail
FDA (US)	Approved	Diabetes, weight management, CV risk reduction, kidney disease; injectable and oral.
EMA (EU)	Approved	Diabetes and weight management.
CDSCO (India)	Approved	Injectable and oral forms available.
WADA	Not prohibited	GLP-1 agonists are permitted.

The NexGen read

The proven baseline

Semaglutide reliably reduces appetite, steadies blood sugar and protects the heart. Results depend on staying on it, eating plenty of protein and doing resistance training. If maximum weight loss is the only goal, the newer dual and triple agonists go further.

References

Wilding JPH, Batterham RL, Calanna S, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med. 2021;384(11):989–1002. doi:10.1056/NEJMoa2032183
Lincoff AM, Brown-Frandsen K, Colhoun HM, et al. Semaglutide and cardiovascular outcomes in obesity without diabetes (SELECT). N Engl J Med. 2023;389(24):2221–2232. doi:10.1056/NEJMoa2307563
Novo Nordisk. Wegovy and Ozempic (semaglutide) prescribing information.