A systematic review has pulled together 26 economic evaluations of the approved weight-loss drugs, and the pattern it reports is worth knowing before anyone quotes “cost-effective” at you. Semaglutide came out ahead of liraglutide consistently enough that the authors call liraglutide generally not cost-effective. Tirzepatide bought the most health of any drug reviewed, and frequently at a ratio payers would accept — but often above what the stingier systems are willing to pay. The review’s closing recommendation is the part that matters most to a person paying cash: economists need to stop letting cost-effectiveness stand in for affordability.
What was reviewed, and what the terms mean
The authors searched Ovid MEDLINE, Embase and government websites for full economic evaluations of approved anti-obesity medications in adults with overweight or obesity, covering tirzepatide, semaglutide, liraglutide, naltrexone/bupropion, orlistat, phentermine and phentermine/topiramate. Twenty-six studies met the inclusion criteria. Methodological quality was graded with the BMJ checklist and reporting quality with CHEERS 2022; the review followed PRISMA and was registered on PROSPERO (CRD420251139475).
Two pieces of jargon carry the findings. A QALY, or quality-adjusted life year, is one year of life in full health — a year lived in worse health counts as a fraction of one. An ICER, or incremental cost-effectiveness ratio, is the extra cost of a treatment divided by the extra QALYs it delivers: the price of one additional healthy year. Health systems set a willingness-to-pay threshold, and an ICER below it is judged worth funding. The threshold is a policy choice, not a fact, and it differs by country — which is why the same drug at the same price can be cost-effective in one system and rejected in another.
Against that scale, the review found semaglutide’s cost-effectiveness variable across studies but consistently better than liraglutide’s. Tirzepatide produced greater health gains and frequently favourable ICERs, yet often exceeded willingness-to-pay thresholds in lower-threshold settings. Among the older drugs, phentermine/topiramate looked economically competitive, which the authors attribute largely to its lower acquisition cost rather than to superior results.
Cost-effective is not the same as affordable
Every one of the 26 studies was conducted in a high or upper-middle-income country, and they were predominantly written from a payer’s perspective — an insurer or a national health system deciding what to cover. That perspective asks whether a population’s health gain justifies a budget’s outlay. It does not ask whether the person swiping a card at the pharmacy counter can cover this month. Those two questions can give opposite answers about the same prescription, and the review names the gap explicitly, calling for clearer distinctions between cost-effectiveness and affordability in future work. If you are paying without insurance, the number that governs your decision is the one on the receipt, not the ICER — our breakdown of what these drugs cost without insurance works from that side of the counter.
The results were also heterogeneous and, in the authors’ words, sensitive to model assumptions. Economic models of obesity drugs have to guess at things nobody has measured yet: how long people stay on treatment, how much weight returns when they stop, and how many heart attacks and diabetes diagnoses are avoided decades later. Change those guesses and the ICER moves.
What is not yet known
This is a narrative synthesis, not a pooled quantitative analysis — the studies were too different to combine into a single number, so no headline figure comes out of it. Direct comparative economic evidence between the newer agents remains limited, meaning most studies compared a drug against standard care rather than against each other, and the ranking above is assembled across studies rather than measured within one. The authors call for long-term real-world data, which is a polite way of saying the models are still running mostly on trial data and assumption. And the review captures list and reimbursement prices as they stood in the published studies; self-pay pricing for this class has moved repeatedly over the past year, and any economic verdict resting on a price is only as current as that price. Nothing here tells an individual what their own treatment will cost or whether an insurer will cover it.
Sources: Jurković M, Fajkić A, Faour AK, Momčilović M, Turčić P, Belančić A. “Economic evaluations of antiobesity medications: A systematic literature review.” British Journal of Clinical Pharmacology, published online 20 September 2026. doi:10.1002/bcp.70825. Review protocol registered on PROSPERO as CRD420251139475.
