The 12-Month Retatrutide Protocol: Dosing, Titration and What to Expect

If you're planning a first order, or trying to work out what a year of this actually involves, the practical questions come down to three: how fast do you step the dose up, where do you stop, and how much of the stuff does that add up to?

This covers all three, plus what a year costs at the prices I actually paid.

Why titration matters

Retatrutide is substantially more potent than Ozempic or Mounjaro. That potency is the reason it produces the results it does — and the reason starting at a therapeutic dose tends to go badly.

Titration exists for one purpose: to let the body adapt gradually, so that side effects — overwhelmingly nausea — stay manageable rather than miserable. People who rush it generally regret it. Severe nausea in week one is the single most common reason people abandon the compound entirely, and it's almost always self-inflicted.

The principle that runs through everything below: only step up if you're tolerating where you are. If you're still queasy, stay put. Weight loss continues at the dose you're on.

The phases

This shape — four weeks per step, roughly a milligram at a time — follows the titration curves used in the clinical trials, adapted to the vial sizes the research route comes in. It assumes one subcutaneous injection per week.

Unit figures below assume the two reconstitutions covered in the mixing guide: 2ml of bacteriostatic water into a 10mg vial (5mg/ml), or 1ml (10mg/ml). For any other vial size or mix, the dose calculator will convert it.

Phase 1 — Starter, weeks 1–4

The tolerance phase. Appetite suppression usually arrives noticeably — for most people, more noticeably than they expected. Nausea is likely in the first fortnight and typically eases by week three. Food stops being interesting. Portions shrink without much conscious effort.

Phase 2 — Building, weeks 5–16

Each step up tends to bring a brief return of mild nausea for three to five days. That's normal and it settles. By 4mg most people are into clearly visible weight loss, and 4mg was one of the key doses carried through the trials.

Phase 3 — Finding a maintenance dose, weeks 17–24

Not everyone goes this far. Plenty of people find 4mg is where they settle — losing steadily, tolerating it well, no particular reason to climb. If that's you, there's nothing to be gained by pushing.

Others go on to 6mg for faster results or to move past a plateau. The Phase 2 trial ran doses up to 12mg; on the research route most people seem to land somewhere between 4mg and 8mg long term.

Higher doses can mean faster loss, but also more of everything else — fatigue, and appetite suppression strong enough that some people have to remind themselves to eat at all. That last one is worth taking seriously rather than treating as a win.

Phase 4 — Maintenance, weeks 25–52

Once you've found your level the job is consistency: same day each week, rotating sites. Loss slows as you approach target weight — that's the body having less to give up, not the compound failing. Plateaus around months six to eight are commonly reported, and they generally break.

How much peptide does a year take?

Everything below assumes 10mg vials. These are arithmetic, not advice — they're here so you can work out your own number instead of guessing.

If you settle at 4mg from week 13

If you settle at 6mg from week 21

If you settle at 8mg from week 25

What that costs

I paid £84.32 for 100mg delivered — £0.84 per milligram. The full breakdown, to the penny, is on the resources page. Applying that rate:

For comparison, a private UK clinic prescribing Mounjaro runs £130–200 a month — somewhere between £1,560 and £2,400 for the same twelve months. That gap is the entire reason this route exists, and it's why the honest accounting matters: the equipment, not the peptide, is where most first-timers overspend.

On ordering

The thing worth understanding before a first order is that you don't yet know where you'll settle. The three totals above differ by nearly 130mg, and which one applies to you isn't knowable until you've been through the titration.

Buying in bulk is cheaper per milligram — that part is real, and my own 100mg purchase worked out 35% better per milligram than the smaller quantity. But bulk-buying a year of something you haven't taken yet, on the assumption you'll tolerate it and stay the course, is a different kind of decision. Reconstituted vials also have a four-to-six week shelf life, so quantity bought is not the same as quantity usable.

Work out the number for the dose you'd realistically settle at, and be honest with yourself about whether you know that yet.

Cumulative use through the year

Tracking the 4mg route, so you can see where you'd be at any point:

What weight loss looks like

Start with what was actually measured rather than what gets quoted. Lilly's Phase 3 trial, TRIUMPH-1 (2,339 participants, results announced 21 May 2026), reported average weight loss at 80 weeks by dose:

So for someone starting at 100kg and settling around 4–6mg, a realistic destination is somewhere in the high 70s to low 80s kg, and the trial took 80 weeks to get there — not 52. A twelve-month figure will land short of the trial's, because the trial itself hadn't finished losing at twelve months.

Two more findings worth having, both from the 12mg group: 45.3% of participants lost 30% or more, and in an extension of 532 people with a starting BMI of 35 or above, average loss reached 30.3% at 104 weeks. Higher starting weight, longer runway, bigger numbers.

What none of this tells you is your own curve. Loss is fastest in the first few months, slows as you approach a natural floor, and stalls for weeks at a time in between. The trajectory matters far more than any individual week — weight moves with hydration, salt, sleep and time of day, and a bad morning on the scales means nothing at all. Losing consistently over a month is the signal. Everything else is static.

I'm tracking my own numbers publicly rather than relying on averages — the progress page has every weigh-in, including the weeks nothing happened.

Common questions

Can I inject more often for faster results?
No. Retatrutide has a half-life of roughly six days, which is what makes weekly dosing work. Splitting doses doesn't accelerate anything — it just produces an uneven drug level and a protocol you can't keep track of.

What if I miss a dose?
Missing by a day or two: people generally inject when they remember and reset the weekly schedule from there. Missing a full week: resume at the same dose rather than doubling up to catch up.

Can I stop and restart?
People do, for holidays, illness, or cost. After a break of more than two or three weeks, tolerance drops — the common approach is to step back a dose level and re-titrate rather than resuming where you left off.

Do I need to diet?
Appetite falls sharply enough that most people eat less without trying. What does matter is protein: losing weight this fast without protecting muscle mass means losing some of it, and that's worth actively avoiding.

When will I see results?
Reduced appetite usually within the first week. Visible loss typically weeks two to four. This is not a compound that rewards judging it by the first fortnight.