What a pound actually costs you

Where the numbers come from

Each brand-name obesity GLP-1 reported a mean weight loss at the end of its pivotal trial, and that figure sits on the FDA label. Those are the values used here, and nothing else:

• Wegovy 2.4 mg (semaglutide) — a mean of 14.9%, measured at 68 weeks in STEP-1 [5].
• Zepbound 5 mg (tirzepatide) — 15.0% at the 72-week mark of SURMOUNT-1 [2].
• Zepbound 10 mg (tirzepatide) — 19.5% at the same 72-week point [2].
• Zepbound 15 mg (tirzepatide) — 20.9%, the largest of the set, again at 72 weeks [2][6].
• Foundayo 17.2 mg (orforglipron) — 11.1% at 72 weeks, taken from the approved prescribing information at the highest dose the label carries [3].
• Saxenda 3 mg (liraglutide) — 8.0%, the oldest and the smallest, at 56 weeks in SCALE [4].

Ask for a shorter run than the trial itself and the figure has to be scaled back. Weight does not come off evenly, so a straight division would flatter the early months. The scaling follows the shape the trials reported along the way: month 1 = 25%, month 3 = 55%, month 6 = 80%, month 9 = 95%, month 12+ = 100% of the loss recorded at the end. Most of it arrives between months 1 and 9 and then levels off, so this is an approximation, and a deliberately cautious one. From there: lbs lost = starting weight × (trial % × time factor) and $/lb = (monthly cost × months) ÷ lbs lost.

Reference table — $/lb lost at common weights (12 months, list price)

Two assumptions hold this table up: a full 12 months on the drug, and cash at the usual US list price — $1,349 a month for Wegovy and for Saxenda, $1,086 for Zepbound, $649 for Foundayo. Neither may be true of you. Put what you actually pay into the calculator above and the number becomes yours.

Read down a column rather than across one and the point of this table appears: at a fixed percentage, what a pound costs barely moves with the weight you start at. Someone beginning at 150 lb and someone beginning at 300 lb land on much the same dollars per pound for the same drug — the heavier person simply sees more pounds. Which is why, in a comparison between two drugs, the percentage is what to look at and your own starting weight is not.

Frequently asked questions

Why not just compare monthly prices?

Because two drugs can charge the same and deliver quite different results. Set a drug at $1,000 a month that takes off 50 lb against one at $800 that takes off 20, and the cheaper one is the worse buy by a wide margin. Dividing by the pounds is what puts efficacy and price on the same axis.

Which GLP-1 costs the least per pound?

Among the brands, and paying list, it is Zepbound at 15 mg. Its 20.9% is the largest figure any FDA-approved obesity drug carries, and Lilly asks roughly what Novo asks for Wegovy, so the extra loss arrives without an extra premium. Compounded semaglutide and tirzepatide can come in below that per pound — see our cheapest compounded semaglutide guide — with the caveat that compounding brings its own quality and supply problems.

Will these numbers hold for me?

They are a projection off trial averages, offered honestly, and they are not a promise. A mean has half the participants above it and half below. Where you land depends on whether you keep taking it, how far up the dose ladder you get, what you eat, how you sleep, and a good deal of biology nobody can read in advance. Plan with it; do not forecast with it.

Why is tirzepatide cheaper per pound at a similar monthly price?

The gap is in the trials. Tirzepatide at 15 mg returned a mean of 20.9% in SURMOUNT-1 [6]; semaglutide at 2.4 mg returned 14.9% in STEP-1 [5]. Spend the same each month and get more pounds for it, and the division comes out lower — the sticker prices barely need to differ at all. We take that gap apart in our tirzepatide vs semaglutide head-to-head.

Where do compounded versions land?

A compounded semaglutide or tirzepatide can bring the month down to somewhere between $150 and $300, and at that price the per-pound figure falls through the floor. It is a different calculation, not a discount on the same one. Our cheapest compounded semaglutide guide carries the current prices, and the supply and quality questions that ought to be settled before any of it matters.

How much does insurance change this?

It changes everything. A plan that covers Wegovy or Zepbound at a copay of $25 to $50 moves the per-pound figure by a factor of ten or more. Replace the list price in the calculator with what you are actually charged and the answer becomes real. On working the coverage itself, see our GLP-1 pricing index.

Important disclaimer

Educational only, and not medical advice. The weight-loss figures projected here are the published means, read from each drug's own FDA prescribing information and from the trial papers in the NEJM behind them. What any one person loses varies a great deal around a mean. The prices assumed are list prices and are unlikely to be what you are charged. GLP Watchdog does not diagnose, does not treat, and does not tell you what to take.

Related tools and research

• Tirzepatide vs semaglutide head-to-head — how the SURMOUNT-1 margin turns into the per-pound gap
• Foundayo vs Wegovy vs Zepbound comparison — the three obesity drugs set against one another
• GLP-1 pricing index — what the brands cost today, in cash and through a plan
• Cheapest compounded semaglutide — what compounding does to the per-pound figure
• GLP-1 weight loss calculator — the same trial curves, plotted week by week
• GLP-1 savings calculator — the gap between what you pay and brand cash pricing