Guide · what to expect

The first year on a GLP-1, in the order things actually happen

The trials that produced the headline numbers ran for 64 to 72 weeks, and the shape of that year is fairly predictable: a long climb on doses nobody stays on, side effects front-loaded into the steps, a maintenance dose somewhere around month four, and a decision at the end that the pricing rarely prepares people for.

Updated 2026-08-235 sources

Nothing here is a prediction about you. It is what the labelling instructs and what the registration trials measured, laid out in the order a year runs, so that the ordinary parts are recognisable as ordinary and the parts worth a phone call stand out.

Months one to four — the climb

Every product in this class starts below its treatment dose and works upward in fixed steps. Wegovy runs 0.25 mg, 0.5 mg, 1 mg and 1.7 mg in four-week blocks, reaching maintenance at week 17. Zepbound starts at 2.5 mg for four weeks — a dose Lilly’s label states plainly “is for treatment initiation and is not approved as a maintenance dosage” — then 5 mg, then 2.5 mg increments at four-week intervals. The full ladders are in Every dose step, and what to do when you miss one.

Two consequences follow, and both get lost in the sales copy. The first is that the dose you were quoted a price for is usually a dose you pass through. The second is that the first four months are the months in which the drug is least like the thing the trials measured — so early weight change is a poor guide to where you will end up, in either direction.

What the side-effect numbers actually were

Most common adverse reactions in the weight-reduction trials, drug against placebo
Reaction	Wegovy 2.4 mg	Placebo	Zepbound 5–15 mg	Placebo
Nausea	44%	16%	25–29%	8%
Diarrhoea	30%	16%	19–23%	8%
Vomiting	24%	6%	8–13%	2%
Constipation	24%	11%	11–17%	5%
Abdominal pain	20%	10%	9–10%	5%
Fatigue	11%	5%	5–7%	3%

From each product’s prescribing information. Separate trials with different populations — this is not a head-to-head comparison, and the placebo columns are there because they are the only honest way to read the drug columns. Note how much of what gets attributed to these drugs also happened on placebo.

Months four to nine — the maintenance dose, and the plateau that is not one

Once the ladder ends, the dose stops moving and the cost usually stops rising with it. This is where the real monthly price of the treatment becomes visible, and where a number of prepaid plans quietly stop being cheap — the arithmetic is worked through in What GLP-1s actually cost in 2026 and The cheapest GLP-1 programmes, with the memberships added back in.

Weight change in the registration trials is steep early and flattens well before the endpoint, which means a slowing rate is the expected pattern rather than a sign of failure. It also means the headline figures — −14.9% at 68 weeks for semaglutide, −20.9% at 72 weeks for tirzepatide — are endpoints of a curve that was still nearly flat when the trial stopped, not a rate that continues.

This is also the stretch in which the composition of the loss matters. Both labels state that these drugs lower body weight “with greater fat mass loss than lean mass loss” — greater than, not instead of. Protein intake and resistance training are the standard countermeasure, and they are conspicuously absent from most subscription products, for the straightforward reason that the subscription does not sell them. The mechanism is in How GLP-1 drugs actually work, and what that explains.

Months nine to twelve — the decision nobody sells you

Around the point the trials ended, the question changes from how well it is working to how long this goes on. The evidence on stopping is consistent and it is not encouraging: weight is substantially regained after withdrawal, in trial extensions and in a systematic review of 37 studies. That is a property of the treatment rather than a personal failure, and it is set out in full in What happens when you stop.

The practical translation is that the monthly figure you have been paying is closer to a standing cost than to the price of a course, and a year in is the point to price it that way — including what happens to insurance, to an HSA balance, or to a Medicare route. Insurance, HSA and FSA for GLP-1s covers the first two; The Medicare GLP-1 Bridge, and the four tests you have to pass covers the third.

A short list of things worth writing down as you go

The date of each dose increase, because the label’s response to a badly tolerated step is to hold at the previous one, and that conversation goes better with dates.
The exact product and dose on the label of what arrives — brand, or compounded, and at what concentration. Compounded vials are where dosing errors happen; see How to tell a regulated GLP-1 seller from a risky one.
What the maintenance dose will cost, obtained in writing before you reach it.
Any planned surgery or procedure, which both labels now say to disclose to the clinician because of the aspiration warning.
Whether anyone has ever ordered bloodwork. In this market, usually nobody has.

Questions

How quickly should weight start changing?

The trials measured a steep early phase that flattens toward the endpoint, but they report population means over 64 to 72 weeks and cannot tell you about an individual month. The more useful early signal is tolerability, because that is what determines whether you reach a maintenance dose at all.

Is it normal for the nausea to come back?

It is the expected pattern at each dose increase, because the gastric-emptying effect is dose-related. Both labels instruct delaying escalation rather than continuing upward when a step is not tolerated. Severe or persistent vomiting is a different matter and a reason to seek care rather than wait.

What if I plateau at a lower dose?

Both labels treat several doses as legitimate maintenance — 1.7 mg or 2.4 mg for Wegovy in adults, 5 mg, 10 mg or 15 mg for Zepbound — and instruct prescribers to choose on response and tolerability. Staying at a lower approved maintenance dose is a clinical decision, not a compromise. Deliberately staying below any approved dose is a different thing: GLP-1 microdosing, and what the trials do not say about it.

Does the first year get cheaper or more expensive?

Generally more expensive, because advertised prices in this market attach disproportionately to starting doses. Ask for the maintenance price at the outset — it is the number that describes the year.

Sources

Everything on this page traces to one of the links below, retrieved on the date shown. Prices and programme terms in this market change without notice — confirm against the provider before you buy.